MLA

Hughes, Langston, 1902-1967. Peterson, Dorothy. Box 8 (Oversize), folder 97. 1950, undated. https://collections.library.yale.edu/catalog/16198545.

APA, 6th edition

Hughes, Langston, 1902-1967. (["Box 8 (Oversize), folder 97"])(1950, undated)[Peterson, Dorothy]. https://collections.library.yale.edu/catalog/16198545.