MLA

Fitzgerald, Robert, 1910-1985. Milano, Paolo. Box 26, folder 987. 1975 Apr 9. https://collections.library.yale.edu/catalog/17093653.

APA, 6th edition

Fitzgerald, Robert, 1910-1985. (["Box 26, folder 987"])(1975 Apr 9)[Milano, Paolo]. https://collections.library.yale.edu/catalog/17093653.