A catalogue of canon and Roman law manuscripts in the Vatican Library, 1987 p. 226 (under Vat. lat. 2648: Guido Fulcodius)
Hedwigs-Codex von 1353, 1972 p. 5 (Klemens IV)
Inquisitoren-Handbücher, 2014 title page (Guido Fulcodii) page 206 (Guido Fulcodii; French; born towards the end of the 12th century in Saint-Gilles-du-Gard in Languedoc) page 209 (he died in Viterbo on either November 28 or 29, 1268)
New Catholic encyclopedia, 1967 (Clement IV, Pope; born Guy Fulcodi, toward the end of the 12th century; his pontificate was from February 5, 1265 to November 29, 1268)