MLA

Butler, Edward Cuthbert, and David Knowles. Western Mysticism : the Teaching of Augustine, Gregory, and Bernard On Contemplation and the Contemplative Life. 3rd ed. New York: Barnes & Noble, 1968.

APA

Butler, E. Cuthbert, & Knowles, D. (1968). Western mysticism : the teaching of Augustine, Gregory, and Bernard on contemplation and the contemplative life. 3rd ed. New York: Barnes & Noble.

Chicago

Butler, Edward Cuthbert, and David Knowles. Western Mysticism: The Teaching of Augustine, Gregory, and Bernard On Contemplation and the Contemplative Life. 3rd ed. New York: Barnes & Noble, 1968.