Placitus Caloirus et Oliva fecit in nobili urbe messane año 1617
This is the Yates-Houghton “Doppia” Portolan, a rare and beautiful masterpiece that delineates a revolution in geographic understanding and represents the dawn of scientifically-anchored cartography.
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This is an original manuscript portolan chart of the Mediterranean and surrounding seaboards. It was drawn on vellum using black, red, blue, and green inks interspersed with gold leaf and compiled at the beginning of the seventeenth century. It was, like most medieval portolan charts, a spectacular objet d’art. However, as we shall see, this portolan chart has an added dimension that makes it unique among all known examples in the history of cartography.
For the sake of clarity, it should be noted that all references to the portolan chart are based on it being displayed horizontally, with the so-called neck on the left side, allowing the geography and place names to be read in the accepted fashion; south is at the bottom, and north is at the top. The portolan chart actually consists of three separate charts:
1. An “Eastern Atlantic Coast” chart depicting the western North Atlantic seaboard, including the coastlines of Spain, Portugal, France, England, Scotland, Ireland, and the Atlantic coast of northwest Africa. This chart has not been adjusted for magnetic declination.
2. A chart of the Mediterranean littoral, the top of two separate Mediterranean charts placed above and below each other. We can call this chart “Mediterranean Traditional” because it also has not been adjusted for magnetic declination.
3. The bottom of the two Mediterranean littoral charts is called “Mediterranean Corrected” because it has been adjusted for magnetic declination.
It is the juxtaposition of charts #2 and #3 — the two contemporary competing views of the Mediterranean — that makes our portolan chart an exceedingly rare cartographic production known in academic scholarship as a doppia (Astengo 2007). Only four such doppia portolan charts are known to exist, all executed by the Oliva family. In addition to ours from 1617, other examples were produced in 1616, 1618, and 1622. However, of these, only the 1618 is similar to this example because the 1616 and 1622 are smaller atlas charts (Conti 1986, pg. 80).
Incredibly, on top of this extreme rarity, an intriguing feature distinguishes this chart from the other doppia: a separate third chart west of the two Mediterranean charts (what we call the “Eastern Atlantic Coast” chart) showcasing the coastline west of Gibraltar. Thus, our portolan chart could also be understood as a triple-chart (a tripla, as it were), of which no other comparable examples are known to exist or have ever been produced.
That said, the mapmaker’s contrasting presentations of the two Mediterranean littorals make this portolan chart a key achievement in the history of cartography. The upper chart represents a classic medieval-style portolan chart, which draws on centuries of Mediterranean chart-making tradition. The lower chart represents a wholly new way of perceiving navigable space, in that it has been modified according to Oliva’s understanding of magnetic declination. The full significance of this shift and its association with the European overseas expansion is further discussed below, but the palpable impact of changing spatial perceptions is patently clear in the adjusted view’s alignment of Crete and Cyprus on the same parallel.
Drawing two charts of the same area on the same chart served a range of purposes and was very much a product of its time. During the course of the sixteenth-century, European understanding of geography had changed dramatically. This new understanding was reflected in the maps of the time, as is seen most clearly in the shift from a Ptolemaic rendition of the world to Mercator’s cylindrical projections.
The change was especially important for ships crossing the Atlantic, as the effects of magnetic declination were much more significant over large distances in open water. The Mediterranean, on the other hand, was not only a bounded body of water but also one that had been navigated and traversed for millennia, since before the time of Ptolemy himself. In other words, it was a well-known, well-described space, with ports at regular intervals along the coast and plenty of islands by which to navigate. Additionally, onboard compass error would often balance magnetic declination error in the Mediterranean. Consequently, figuring out magnetic declination within the Mediterranean itself was not the primary focus of navigators and cartographers working on the problem. Determining its effects was far more important in the Atlantic.
Why, then, did Oliva go through such incredible efforts to create a chart depicting not only a new understanding of the Mediterranean, but to do so alongside the old, outdated understanding? The best answer to this question is that it allowed pilots and other navigators to directly compare the two perspectives. At the time of its production, the consequences of magnetic declination were not yet fully understood, nor had the calculations to establish it been formalized to the point of agreement. In other words, this chart was produced in a short but highly experimental stage of cartographic history, one in which our established ideas of the world were dramatically challenged and changed. This chart is a fine representation of this paradigm-shift; it is essentially the illustration of a completely new world-view taking hold. On a more practical level, one might argue that this chart was designed with the explicit intention of creating a tool that embodied this change. Moreover, it provided the onboard navigator with comparable views of the old and new ways of reading the maritime sphere. And finally, though on a more subtle level, it highlighted the modernity of the chart and its maker’s knowledge and skill.
Comparing the two Mediterranean charts reveals that the rendition of toponyms differs significantly, reflecting the mapmaker’s ambition to underline distinctions between the old and new ways of composing a portolan chart. In the upper chart, smaller islands have been labeled in the traditional nautical style by denoting place-names next to the island in question. In the bottom chart, however, these labels have been replaced with numbers, allowing space to designate a much larger number of islands (for example, in the Aegean or Adriatic). The numbers are explained in two tabled legends placed in Anatolia and the Balkans, respectively. This condensed way of depicting an archipelago by use of a legend was an entirely new feature in portolan charts, but it aligned well with the overall ambition of precision and accuracy in that it allowed for more physiographic detail.
In the “Eastern Atlantic Coast” chart, which, like the upper Mediterranean chart, has not been adjusted to compensate for magnetic declination, England and Scotland are depicted as two separate islands, despite the fact that the physical reality was well established. Similarly, Ireland has been disproportionately elongated, perhaps in an attempt to align it visually with the rest of the British Isles. The general depiction of the British Isles tells us that in no way was this chart intended for serious navigational use in these regions. Rather, they are emblematic inclusions which allow users to align the new world-view properly with the old.
As with all portolan charts, the chart is hand-drawn, not printed, and executed by a master hand. Its elements are depicted in different colors so that while coastlines and secondary port names are drawn in brown, the larger ports and coastal emporia are highlighted in red, allowing for easier identification. The chart also includes most of the principal rivers that feed into the Mediterranean, which are marked in a bright blue. Two rivers worth noting are the Sebou and Guadalquivir, located in Morocco and Spain, respectively. They are important because they have been included in all three charts of the portolan chart and, consequently, allow the three tightly-packed charts to be distinguished. The Sebou River is unlabeled but runs into the Atlantic immediately south of the Tangier promontory on all three charts. The Guadalquivir, labeled ‘Siniglia’ on all three, is shown extending from Seville into the Atlantic on the European side. By identifying each set of rivers, one can easily separate the three charts both visually and conceptually.
Throughout the chart and along its fringes, elaborate pictorial decorations in a multitude of colors are found. A foliated frieze in red, blue, and brown, and similar in appearance to a stylized arabesque, bounds the entire space and emphasizes the chart as an aesthetic aspiration as well as a functional or scientific one. The chart carries all the decorative elements of a traditional portolan chart, including real and imagined beasts, fleets of different kinds of ships, and stylized representations of cities. In fact, it is so rife with details that they can hardly be fully encapsulated, even in a comprehensive description such as this. The abundance of detail and the potential for continuously discovering new and surprising details are qualities that have made this chart one of the most revered and desired charts from this particular period. It is, in effect, the apex of a centuries-long portolan chart tradition.
Most noteworthy in the ornamental repertoire are perhaps the pictorial insertions. Dominant among the images are stylized depictions of great urban centers dotted around the littoral. Most of these are identified both by name and by means of a banner, but some of the more renowned ports in Christendom also include explicitly identifiable features, revealing Oliva’s attention to detail and the superior quality of his work. Eighteen cities are depicted on the top chart and sixteen on the bottom. The difference in number is only due to the fact that two generic Ottoman cities in Asia Minor have been replaced by one of the legends in the lower chart. Among the political entities identifiable by their banner are Genoa, Venice, Catalonia, Castille, the Holy Roman Empire, and, of course, the Ottoman Empire. The latter clearly dominates North Africa and the East Mediterranean, although there are several Castilian strongholds in Morocco. As mentioned, many of the great European ports have clearly recognizable traits. Examples include the large enclosed port of Marseille and the Lanterna (lighthouse) of Genoa. In Venice, Piazza San Marco, St Mark’s Cathedral, and the Palace of the Doge are all visible in the representation of the city.
The use of flags to overlay the nautical chart with both an aesthetic and a political dimension is one characteristic that makes this chart stand out among its peers. In addition to the banners flying over cities, a notable feature is found in Malta and Rhodes’ attribution to the Knights Hospitaller. This is achieved by coloring the islands themselves in the red and white colors of the order. A similar form of attribution was made for Chios and Lanzarote (Canary Islands) in the top chart, only now in inverted color, recognizing them as subjects of Genoa. However, in the bottom chart, only Lanzarote continues to fly the Genoan colors, reflecting that Chios had fallen to the Ottomans in 1566. This subtle yet important distinction underlines that the difference between the two charts was not just a technical one: the upper chart depicts a world that has been eclipsed by a new vision at the bottom. As a deliberate and forceful juxtaposition of two clashing world-views, the chart is, essentially, an early manifestation of the intellectual aspirations powering the Scientific Revolution and even the Enlightenment of a century later.
Another powerful visual feature is the bestiary represented on this portolan chart. Oceanic spaces are decorated with sea monsters, fleets of sailing ships, and convoys of galley ships. We find depictions of palms, oases, and exotic animals on land, including lions, camels, a unicorn, an ostrich, and various forms of wild game.
On the right side of the chart, or rather at its eastern fringe, there are two mirror depictions of Calvary topped by the three crosses. The central cross is larger than its flanking counterparts and blue rather than red. The two depictions of Golgotha are virtually identical, save for one little detail. Whereas the flanking red crosses of the upper chart are simple crossed lines, on the lower chart these have been elaborated slightly by adding an extra crosslet on each arm. This is a well-known and widely used symbol denoting emphasis on the four evangelists and their gospels, though its exact connotation on this chart is unclear. The earliest known use of this symbol dates to the early fifteenth century, but it had not become widespread before the sixteenth century, and it may thus simply be intended as another visual denominator of the old and new visions of the world.
The weight attributed to Christian symbolism by Oliva and his family can also be deciphered from another aspect of the chart, though this is no more than a blank space. At the beginning of this description, it was mentioned that the chart had a neck at its top or at the left side. Creating portolan charts in this shape may seem odd at first glance, but this was primarily a practical element. Charts that were used on voyages were kept rolled up in cabinets or drawers until they were needed. The neck created an additional length of vellum that wrapped around the chart proper, after which a string or clasp could hold it together. By including a neck, the chart itself was protected somewhat from the wear and tear associated with unfurling it. Although the neck’s visual space remains blank on this chart, the most common use of such spaces was for the miniature or logo of the mapmaker. From similar portolan charts executed by Joan Oliva in 1610 (Pflederer 2012, pg. 98) and 1618 (Astenga 2008) respectively, we know that the Oliva Family in Messina used the highly symbolic scene of a crucified Christ flanked by two saints (evangelists?) as their formal logo.
In addition to the abundance of coastal place-names and islands, an elaborate rhumb line network, anchored by thirteen beautiful wind roses, superimposes the chart. Rhumb lines were a defining feature of portolan charts, helping pilots to plot a reasonable course and subdividing the maritime sphere into a comprehensible network of sightlines and wind directions. Despite gradually being superseded by Mercator’s projection and other early versions of the geographic coordinate system (longitude and latitude), the rhumb line network continued in use. The most likely explanation for its resilience can be found in the internal logic of the network and the fact that it had worked so well for so long. Pilots and navigators were not scholars; they were sailors, and they needed something that was reliable to them. Especially in bounded maritime spaces such as the Mediterranean, rhumb lines continued to be used in maps and charts for centuries.
Of the thirteen colored wind roses on the portolan chart, twelve of them have eight winds or lines emanating from their center. The thirteenth and largest wind rose is located at the bottom center. Even though it is halved, this rose has 32 winds and creates the chart’s primary axes. Along these axes, a number of interstices are created by four of the minor wind roses, which in turn link to the remaining roses of the chart. Of these remaining wind roses, two sit on either side of the central scale bar. Brownish in color, these angle in a different direction than the rest of the roses and denote the axis of the maestro-transmontana winds (Conti 1986, pg. 78). When combined, the winds of the roses form the rhumb line network that covers the entire chart.
The adjustment of the lower chart according to perceived magnetic declination is more apparent when comparing the two nodes of convergence (not endowed with a wind rose) shown in the eastern Mediterranean. While the traditional or ‘medieval’ style top chart shows this node roughly halfway between Crete and Cyprus, the adjusted chart at the bottom places it directly south of Crete. In general, there can be little doubt that charts adjusted for magnetic declination convey the relative positioning of landmasses more accurately than their non-adjusted forebears, although Oliva’s chart is not entirely without problems.
The portolan chart has many aesthetic features that also perform a specific function. The central scale bar that visually separates the two Mediterranean charts is adorned to resemble an elaborate cartouche-like flurry of colors and forms held in place by the brown transmontana wind roses discussed above. Immediately east of this main bar, just under the chart’s central parallel, we find a secondary central scale. Another two elaborate scales have been inserted at the top and bottom of the portolan chart’s western end.
Given its artistic excellence and scientific importance, the richly decorated Yates-Houghton “Doppia” Portolan Chart can be characterized as a missing link between medieval and modern conceptualizations of the world. It is an object of transition and adaptation, and a testimony to human ingenuity and creativity.
Portolan charts, magnetic declination, and early modern charting
Portolan charts are hand-drawn manuscript charts designed to assist navigators in plotting a safe course from one port to another, usually across an open body of water. The concept was first developed in thirteenth century Italy, and most portolan charts do indeed focus on the Mediterranean. The tradition continued until the seventeenth century, at which time charts were more often corrected for magnetic declination and nautical charts increasingly were printed rather than hand-drawn. Portolan charts were generally drawn on vellum using different color inks and were often embellished with silver and gold. At the height of their popularity, exquisite charts of this type were produced throughout the Mediterranean region. And because they were only made in a limited number and often used onboard ships, very few examples have survived.
Our exquisite and extremely rare specimen is consequently not only special in that it has survived and was made by one of the most renowned chart-makers of the time, but also in that it represents a crucial point in cartographic history; a short span in which new ideas of how to map the world were replacing the old. Seamanship was a conservative business, mistakes often carrying immense cost to life and cargo. But the need for better and more accurate systems of navigation had become paramount following the opening of the Atlantic Ocean in the late fifteenth century. When crossing the vast stretches of open water to reach the New World, accurate navigation suddenly meant the difference between life and death. Out there, the consequences of incorrect observations and calculations, documented by sailors in the Old World for at least a few centuries, became so palpably dangerous that it was a problem that had to be resolved quickly. One corrective was the measurement of latitude using an astrolabe to measure the altitude of the sun; this was first adopted by the Portuguese in the mid-sixteenth century. The other important corrective was the delineation of magnetic declination.
Magnetic declination is essentially the local deviation between Magnetic North and True North (i.e., the Earth’s rotational axis). As the deviation is created by dynamic fluctuations in the Earth’s magnetic field, the spatial deviation is not static but changes over time and space. The adaptation of mapmaking to deal with this phenomenon can in many ways be viewed as the birth of modern cartography (i.e., the science of accurately mapping three-dimensional space on a two-dimensional plane). It also represents a concrete shift between maps as conceptualized landscapes – epitomized in the Ptolemaic tradition – and charts as tools for efficient trans-oceanic navigation.
The latter’s rise is clearly seen in the introduction and growth of portolan or navigational charts from the fourteenth century on. Portolan charts mostly focused on guiding mariners from one port of call to the next, preferably by the most direct route possible. The term comes from the Italian word portulano, as in related to harbors or ports, and would probably have been coined in Italy’s great merchant cities. Early portolan charts were functional, often used for trade, and were broadly recognized for their relative accuracy. Consequently, they would usually depict a finite and well-known space such as the Mediterranean. Sometimes included would be sightlines meant to support navigation away from the coast. As the concept developed, it grew into what would become one of the most widely used navigational tools in pre-modern times, namely rhumb line or wind rose networks.
The global European voyages that began at the end of the fifteenth century changed Europe’s outlook on the world for good. Navigation was no longer just a question of trade and transport but now represented the key skill for nations with imperialist ambitions. Despite all of this, most of the charts produced in the first half of the sixteenth century contain no reference to the above-mentioned observations of magnetic deviation. By the end of the century, however, a paradigm shift in cartography had taken hold, and mapmaking soon changed as an industry. Not only were there new and different customers, but also new and entirely different purposes.
The shift was evident in a number of ways. Precision graticules increasingly became standard, and published nautical charts and atlases were now consistently oriented around wind rose networks that guided captains between identified ports of call. With regard to magnetic deviation, the first important innovation became the use of hydrographers to correctly adjust the axis of larger charts. The novel understanding of the mechanisms of navigation resulted in a flurry of new portolan-style charts, adjusted to take the latest developments into account. Our chart constitutes perhaps one of the most visually dramatic attempts to accomplish exactly that.
That our chart fits perfectly in this short window of transition is confirmed by looking at the other surviving portolan charts from the hand of Joan Oliva. We have already mentioned his 1610 portolan chart of the Mediterranean in relation to the logo or miniatura in the neck. More important is the fact that this chart, which predates ours by only seven years, consists of only a single unadjusted chart in the old style.
Joan Oliva is known to have produced a number of double charts of the Mediterranean, gradually perfecting his revised vision. When he published his magnificent fifteen-chart atlas of the Mediterranean from Messina in 1614, he decided to include two charts of the same part of the Eastern Mediterranean. The charts were at different scales and applied different rotational axes: one using the old counterclockwise rotation, the other an adjusted view that aligned Crete and Cyprus on the same parallel. This was the first time that Oliva addressed the problem of magnetic declination, and in a second atlas produced two years later, he makes only very slight amendments before including the same two charts again.
Oliva’s desire to innovate his craft was most likely brought on by reading Bartolomeo Crescenzio’s critique of navigation. Crescenzio, who was the Commodore of the Papal fleet, had criticized the Messina school of cartography in a debate in the year 1595. This critique was formalized, elaborated, and expanded in his Nautica mediterranea di Bartolomeo Crescentio Romano, which was published in Rome in 1602. The crux of Crescenzio’s argument against the Messina school was a critique of the paucity of hydrographically-adjusted charts and an admonition of those not accommodating the effects of magnetic declination. Oliva may have had an opportunity to discuss the points of his critique with Crescenzio directly, as both men seem to have been in Messina at the same time. Whatever the case, Oliva took the critique to heart and spent more than a decade working on the problem before he began implementing actual changes in his charts. Part of his motivation was undoubtedly due to the increasing popularity of North European revisionist models. As a businessman, Oliva would also have been keenly aware of shifts in the market and the rapidly growing influence of Dutch cartographers in particular.
When Oliva issued his next chart showing magnetic deviation in 1617, his understanding and ambitions had grown considerably. This is our chart, which has been extensively discussed and described above. What is important to note here is that this chart no longer was experimental. Oliva had worked on the problem of magnetic declination for years, and now, finally, he was ready with a chart that dealt with the problem both efficiently and elegantly. His upgraded understanding of how to represent the consequences of magnetic deviation meant that he felt confident enough to portray the two visions in obvious juxtaposition, as if for the whole world to judge his conclusions.
The bottom adjusted Mediterranean chart has been rotated nine degrees diminishing from west to east (clockwise), which despite being the opposite of actual reality, appears to have been the hydrographic consensus at the time. One year later, in 1618, Oliva produced a final double chart from his new base in Livorno. This chart, which is currently held in the Biblioteca Gambalunga in Rimini, built on his original visionary chart from the year before, but was more streamlined for functionality and market appeal. In other words, Joan Oliva was at the forefront of his craft, not only aspiring to the highest degree of accuracy but incorporating crucial cartographic innovations in the traditional portolan charts for which he and his family were famous. This chart stands out as the culmination of his thought process and the epitome of his transitional output. It is a masterpiece of both thought and execution, and a miracle of survival.
This chart has the distinction of having been owned by two of the most important book and manuscript collectors of the late nineteenth and twentieth century, Henry Yates Thompson and Arthur Houghton Jr. The names Houghton and Yates Thompson rightfully belong in the pantheon of collectors and patrons of the arts such as Henry Huntington, Paul Mellon, and J. P. Morgan.
Christies New York, October 18, 2020 (Lot 3).
Henry Yates Thompson
Henry Yates Thompson (1838-1928) was a newspaper proprietor, a Liberal politician, and a meticulous collector of medieval and early modern manuscripts. Originally from Liverpool, he was educated at Harrow, where he was head boy, and Trinity College, Cambridge. At eighteen, his grandfather left him an extraordinary collection of ten manuscripts, which included a portolan-style chart. However, it was not until the 1880s, as his career began to wind down, that he developed his serious focus on collecting.
At first, Yates Thompson bought selectively from many famous collections that were for sale in the 1880s and 1890s, including the library of Sir Thomas Phillipps, the Firmin Didot collection, the Hamilton manuscripts (1889), and John Ruskin’s collection (1902). In 1897, Yates Thompson purchased the manuscripts known as the Appendix, a supplement to the main collection of the final Earl of Ashburnham, for £30,000. The Appendix numbered over 200 manuscripts.
Faced with a burgeoning number of rare and exquisite manuscripts, Yates Thompson took the unusual decision to only keep the best—those with excellent provenance and of the highest aesthetic quality—one hundred manuscripts. He sold all the lesser volumes, including 177 items from the Appendix. He also began to publish descriptive catalogs of his collection; he would eventually publish four such catalogs (1898-1912) with venerable academics and experts like M. R. James, S. C. Cockerell, and G. F. Warner as contributors. He also published a set of illustrations of the collection (1907-1918) to complement the catalogs.
In the final volume of the Illustrations, Yates Thompson surprised again, this time announcing that he would sell the Hundred; his sight was declining due to cataracts. They were auctioned at Sotheby’s in 1919, 1920 and 1921; certain volumes were also gifted to institutions such as the British Museum, the Fitzwilliam Museum, and the Royal Geographical Society. He also presented his example of a Josephus manuscript to the Bibliotheque Nationale; their copy was defective. For this, he was made a chevalier of the Légion d’honneur.
His wife, Elizabeth, outlived Yates Thompson, who died at 90. Elizabeth was also a keen collector and an expert on their manuscripts. She lived until 1941 and, upon her death, gave the remaining works to the British Museum. Today, they are known as the Yates Thompson Collection and are held in the British Library.
Nina R. and Arthur Houghton Jr.
Arthur Houghton Jr. had an avid interest in literature and the English language which started during his undergraduate years at Harvard. He focused his early energies on collecting manuscripts and first edition books by authors including Milton, Pepys, Shakespeare, Spenser, Keats, and Lewis Carroll, later extending his bibliophilic tendencies to include landmark works such as two Gutenberg Bibles and the unparalleled Shahnameh of Shah Tahmasp. He formed an outstanding collection of miniature books, English silver, and a small but exquisite group of paintings by Thomas Sully, Jean Honore Fragonard, and Francesco Guardi.
W.H. Bond, then curator of the Houghton Library at Harvard, provided the foreword to the catalog for the sale of Mr. Houghton’s private library at Christie’s in 1979, noting:
In 1957, writing about Arthur Houghton’s library in The Book Collector, I remarked, ‘As one ranges the shelves, two governing principles of the collection quickly became apparent: association and, even more strongly, condition.’ I might have added two other characteristics, but these seemed to me obvious: intrinsic importance and absolute rarity.
In addition to endowing the Houghton Library as a repository for Harvard’s collections of rare books and manuscripts, Mr. Houghton was a board member of the New York Philharmonic and the Metropolitan Museum of Art, vice chairman of a committee to create Lincoln Center, vice president of the Pierpont Morgan Library, trustee and chairman of the Cooper Union, trustee and chairman of the Parsons School of Design, and co-founder of the Corning Museum of Glass.
Arthur Houghton married Nina Rodale in 1972, and they lived on the Eastern Shore of Maryland with their children. Nina Rodale Houghton was a life-long supporter of educational institutions and causes, serving as Trustee of the Wye Institute, Trustee of Goucher College, a board member of the Columbus Center in Baltimore, and an advisory group member to the Maryland Department of Natural Resources. She was a member of the Board of Visitors to Johns Hopkins Medicine, a member of the Board of Visitors of University of Maryland College Park, and a board member of the Aspen Institute. Before marrying Mr. Houghton she worked with the Sea Mammal Motivational Institute (SEAMAMM) studying and training seals and sea lions aboard a research vessel with her family for four years; this episode was covered in depth in a November 1968 National Geographic article.
Manuscript map on a large sheet of vellum with tacking marks at the edges, particularly right edge. Archivally and reversibly mounted.
2007 The Renaissance Chart Tradition in the Mediterranean, History of Cartography 3,1: 174-262
1986 Un’originale carta nautica del 1617 a firma di Placidus Caloiro et Oliva, Geografia 9: 77-86
1993 S Conti, “Le carte nautiche ‘doppie’ della famiglia Olives-Oliva,” in Momenti e problemi della geografia contemporanea: Atti del Convegno Internazionale in onore di Giuseppe Caraci, geografo storico umanista (Rome: Centro Italiano per gli Studi Storico-Geografici, 1995), 493–510
Pflederer, Richard L.
2012 Finding their Way at Sea: The Story of Portolan Charts, the Cartographers who Drew Them and the Mariners who Sailed by Them. Houten: Hes & De Graaf