MLA

Hughes, Langston, 1902-1967. Arpa, Guillermo. Box 8, folder 184. 1946 Aug 25. https://collections.library.yale.edu/catalog/33219454.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 8, folder 184"])(1946 Aug 25)[Arpa, Guillermo]. https://collections.library.yale.edu/catalog/33219454.