MLA

Hughes, Langston, 1902-1967. Ellington, Duke. Box 19, folder 255. 1875-1978. https://collections.library.yale.edu/catalog/16207036.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 19, folder 255"])(1875-1978)[Ellington, Duke]. https://collections.library.yale.edu/catalog/16207036.