MLA

Lewis, Sinclair, 1885-1951. [Poems]. Box 39, folder 349-352. 1905-1950. https://collections.library.yale.edu/catalog/17116525.

APA, 6th edition

Lewis, Sinclair, 1885-1951. (["Box 39, folder 349-352"])(1905-1950)[[Poems]]. https://collections.library.yale.edu/catalog/17116525.