C. Raymond Beazley

The Dawn of Modern Geography. Vol. III. A History of Exploration and Geographical Science from the Middle of the Thirteenth to the early Years of the Fifteenth Century (c. A.D. 1260–1420). With reproductions of the Principal Maps of the Time. Chap. II. The Great Asiatic Travellers, 1260–1420. Part I. The Polos, 1260–1295, pp. 15–160.