MLA

Johnson, James Weldon, 1871-1938. James Weldon Johnson and Paul Dunbar. Box 108, folder 923. circa 1900. https://collections.library.yale.edu/catalog/16744477.

APA, 6th edition

Johnson, James Weldon, 1871-1938. (["Box 108, folder 923"])(circa 1900)[James Weldon Johnson and Paul Dunbar]. https://collections.library.yale.edu/catalog/16744477.