[Lewis], Claude B. (brother)
MLA
Lewis, Sinclair, 1885-1951. [Lewis], Claude B. (brother). Box 54, folder 769. undated. https://collections.library.yale.edu/catalog/10516618.
APA, 6th edition
Lewis, Sinclair, 1885-1951. (["Box 54, folder 769"])(undated)[[Lewis], Claude B. (brother)]. https://collections.library.yale.edu/catalog/10516618.