MLA

Fulton, John F. (John Farquhar), 1899-1960. McCullough, Warren. Box 121, folder 1651. 1933-1956. https://collections.library.yale.edu/catalog/33513495.

APA, 6th edition

Fulton, John F. (John Farquhar), 1899-1960. (["Box 121, folder 1651"])(1933-1956)[McCullough, Warren]. https://collections.library.yale.edu/catalog/33513495.