Citazione Stile APA (7a Edizione)

Cheetham, N. (1982). Keepers of the keys: A history of the popes from St. Peter to John Paul ll. Charles Scribner's.

Citazione stile Chigago Style (17a edizione)

Cheetham, Nicholas. Keepers of the Keys: A History of the Popes from St. Peter to John Paul Ll. New York: Charles Scribner's, 1982.

Citatione MLA (9a ed.)

Cheetham, Nicholas. Keepers of the Keys: A History of the Popes from St. Peter to John Paul Ll. Charles Scribner's, 1982.