MLA

Hughes, Langston, 1902-1967. Latin American Letters. Box 226, folder 3733-3734. 1938-67, n.d.. https://collections.library.yale.edu/catalog/17034011.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 226, folder 3733-3734"])(1938-67, n.d.)[Latin American Letters]. https://collections.library.yale.edu/catalog/17034011.