MLA

Fitts, Dudley, 1903-1968. Laughlin, James. Box 1, folder 35. 1941-1946, undated. https://collections.library.yale.edu/catalog/17428882.

APA, 6th edition

Fitts, Dudley, 1903-1968. (["Box 1, folder 35"])(1941-1946, undated)[Laughlin, James]. https://collections.library.yale.edu/catalog/17428882.