MLA

Hughes, Langston, 1902-1967. McKay, Claude. Box 20, folder 279. 1875-1978. https://collections.library.yale.edu/catalog/16207056.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 20, folder 279"])(1875-1978)[McKay, Claude]. https://collections.library.yale.edu/catalog/16207056.