APA (7th ed.) Citation
Cheetham, N. (1982). Keepers of the keys: A history of the popes from St. Peter to John Paul ll. Charles Scribner's.
Chicago Style (17th ed.) Citation
Cheetham, Nicholas. Keepers of the Keys: A History of the Popes from St. Peter to John Paul Ll. New York: Charles Scribner's, 1982.
MLA (9th ed.) Citation
Cheetham, Nicholas. Keepers of the Keys: A History of the Popes from St. Peter to John Paul Ll. Charles Scribner's, 1982.
Warning: These citations may not always be 100% accurate.