APA

Ullmann W., . (1960). The medieval papacy. London: Aquin press.

Chicago

Ullmann Walter, . 1960. The medieval papacy. London: Aquin press.

Harvard

Ullmann W., . (1960). The medieval papacy. London: Aquin press.

MLA

Ullmann Walter, . The medieval papacy. London: Aquin press. 1960.