Cheetham, N. Keepers of the keys: A history of the Popes from St. Peter to John Paul II.
芝加哥风格引文Cheetham, Nicolas. Keepers of the Keys: A History of the Popes from St. Peter to John Paul II.
MLA引文Cheetham, Nicolas. Keepers of the Keys: A History of the Popes from St. Peter to John Paul II.
警告：这些引文格式不一定是100％准确.