MLA

Johnson, James Weldon, 1871-1938. Hart, Albert Bushnell. Box 9, folder 198. 1938. https://collections.library.yale.edu/catalog/16747988.

APA, 6th edition

Johnson, James Weldon, 1871-1938. (["Box 9, folder 198"])(1938)[Hart, Albert Bushnell]. https://collections.library.yale.edu/catalog/16747988.