MLA

Wilson, Edmund, 1895-1972. Fitzgerald, Zelda. Box 27, folder 665-666. 1929-45, n.d.. https://collections.library.yale.edu/catalog/11872987.

APA, 6th edition

Wilson, Edmund, 1895-1972. (["Box 27, folder 665-666"])(1929-45, n.d.)[Fitzgerald, Zelda]. https://collections.library.yale.edu/catalog/11872987.