MLA

Hughes, Langston, 1902-1967. Peterson, Jerome Bowers. Box 20, folder 289. 1899-1923. https://collections.library.yale.edu/catalog/16207066.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 20, folder 289"])(1899-1923)[Peterson, Jerome Bowers]. https://collections.library.yale.edu/catalog/16207066.