MLA

Hughes, Langston, 1902-1967. Adler, Stella. Box 2, folder 39. 1944 May 9. https://collections.library.yale.edu/catalog/32604519.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 2, folder 39"])(1944 May 9)[Adler, Stella]. https://collections.library.yale.edu/catalog/32604519.