The owl and the nightingale.
Cleanness. St. Erkenwald.
Translated and introduced by Brian Stone.

APA Citation

Guildford, N. de., Stone, B. (1971). The owl and the nightingale: Cleanness. St. Erkenwald. [Harmondsworth, Eng.: Penguin Books.

MLA Citation

Guildford, Nicholas de, fl. 1250, and Brian Stone. The Owl And the Nightingale: Cleanness. St. Erkenwald. [Harmondsworth, Eng.: Penguin Books, 1971.

Warning: These citations may not always be complete (especially for serials).