Roel Zemel, The new and the old Perceval. Guillaume's «Fergus» and Chrétien's «Conte du Graal», Bibliographical Bulletin of the International Arthurian Society, 46, 1994 : p. 324-342
Whereas Chrétien de Troyes's Perceval was emancipated from the amour-chevalerie theme of pre-Grail romance and developed into a Christian knight, Guillaume le Clerc willingly re-introduces the profane element in adapting Chrétien's textDans IMB 29/1 n° 3127/