MLA

Hughes, Langston, 1902-1967. Coppock, Khary Kamau. Box 19, folder 247. 1973. https://collections.library.yale.edu/catalog/16207029.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 19, folder 247"])(1973)[Coppock, Khary Kamau]. https://collections.library.yale.edu/catalog/16207029.