Cita APA (7a ed.)

Cheetham, N. Keepers of the keys: A history of the Popes from St. Peter to John Paul II.

Cita Chicago Style (17a ed.)

Cheetham, Nicolas. Keepers of the Keys: A History of the Popes from St. Peter to John Paul II.

Cita MLA (8a ed.)

Cheetham, Nicolas. Keepers of the Keys: A History of the Popes from St. Peter to John Paul II.