APA (7th ed.) Citation

Shannon, A. C. (1980). The popes and heresy in the thirteenth century. AMS Press.

Chicago Style (17th ed.) Citation

Shannon, Albert Clement. The Popes and Heresy in the Thirteenth Century. New York: AMS Press, 1980.

MLA (9th ed.) Citation

Shannon, Albert Clement. The Popes and Heresy in the Thirteenth Century. AMS Press, 1980.