MLA

Fitzgerald, Robert, 1910-1985. Saint-John Perse. Box 33, folder 1250. 1960-66, n.d.. https://collections.library.yale.edu/catalog/17093656.

APA, 6th edition

Fitzgerald, Robert, 1910-1985. (["Box 33, folder 1250"])(1960-66, n.d.)[Saint-John Perse]. https://collections.library.yale.edu/catalog/17093656.