Ronald Walpole, Charlemagne's Journey to the east: the French translation of the legend by Pierre de Beauvais, Semitic and Oriental Studies : A Volume Presented to William Popper on the Occasion of his Seventy-Fifth Birthday October 29, 1949, University of California Publications in Semitic Philology, Berkeley-Los Angeles, University of California press, 1951 : p. 433-456