Sir Gawain and the Green knight:
APA Citation
Arthur, K., Gollancz, I., Serjeantson, M. S. (Mary Sidney)., Day, M. (1940). Sir Gawain and the Green knight. London: Pub. for the Early English text society by H. Milford, Oxford university press.
MLA Citation
Arthur, King, Israel Gollancz, Mary S. (Mary Sidney) Serjeantson, and Mabel Day. Sir Gawain And the Green Knight. London: Pub. for the Early English text society by H. Milford, Oxford university press, 1940.
Warning: These citations may not always be complete (especially for serials).