Послания из вымышленного царства

Richard J. Orient et Occident au Moyen Age; contacts et relations (XIIe – XVe s.). London, 1976.
Richard J. La Papaute et les missions d'Orient au moyen age (XIIIe -XVe s.). Rome, 1977.
Richard J. Croises, missionaires et voyageurs. London, 1983.
Richard J. Croisades et Etats latins d'Orient. Aldershot, 1992.
Ross E. D. Prйster John and the Empire of Ethiopia // Travel and Travelers of the Middle Ages / Ed. A. P. Newton. New York, 1926. P. 174 – 194.
Witlkower R. Marvels of the East. A Study in the History of Monsters // Journal of the Warburg and Courtland Institutes. 1942. Vol. 5. P. 159 – 197.
Wright J. K. The Geographical Lore of the Time of the Crusades. New York, 1965.
Yule H. Cathay and the Way Thither // 2nd edition by H. Cordier. 4 vols. London, 1913 – 1916. – (Hakluyt Society. Ser. 2: Vols, 33, 37, 38, 41).