APA (7th ed.) Citation

Pennington, M. B. (1992). The Cistercians. Religious order series.

Chicago Style (17th ed.) Citation

Pennington, M. Basil. "The Cistercians." Religious Order Series 1992.

MLA (8th ed.) Citation

Pennington, M. Basil. "The Cistercians." Religious Order Series, 1992.

Warning: These citations may not always be 100% accurate.