MLA

Fitzgerald, Robert, 1910-1985. Bishop, Elizabeth. Box 4, folder 131. 1949-79. https://collections.library.yale.edu/catalog/17093643.

APA, 6th edition

Fitzgerald, Robert, 1910-1985. (["Box 4, folder 131"])(1949-79)[Bishop, Elizabeth]. https://collections.library.yale.edu/catalog/17093643.