found: Biblioteca apostolica vaticana. Manuscript. Vat. lat. 425 [MI] between 1951 and 1959:fol. 1r (Petri. Ferrici. episcopi. Tirasonensis)
found: Hierarchia Catholica medii aevi, 1913- :v. 2, p. 17 (Petrus Ferrici ep. Tirasonen = tit. s. Sixti (Tirasonensis) d. 1478 Sept. 25)
found: Journal of library history, v. 17, no. 3 (1982):p. 274 (Petrus Ferriz; bishop of Tarazona, Spain, from 1464 to 1478)
found: Moroni, G. Dizionario di erudizione storico-ecclesiastica(Ferrici, Pietro; b. 1413; d. 1477)
found: Catholic encyclopedia:v. 15, p. 452 (under Tarazona: Cardinal Pedro Ferriz)
found: OCLC, Feb. 22, 2010(hdg.: Ferrici, Petrus, d. 1485)