MLA

Johnson, James Weldon, 1871-1938. Unidentified. Box 103, folder 870-871. circa 1900. https://collections.library.yale.edu/catalog/2110141.

APA, 6th edition

Johnson, James Weldon, 1871-1938. (["Box 103, folder 870-871"])(circa 1900)[Unidentified]. https://collections.library.yale.edu/catalog/2110141.