MLA

Van Vechten, Carl, 1880-1964. Long, Avon, as Sportin' Life in Porgy and Bess," musical composed by George Gershwin, libretto by DuBose Heyward and Ira Gershwin. Box 223. 1942 March 24. https://collections.library.yale.edu/catalog/2019639.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 223"])(1942 March 24)[Long, Avon, as Sportin' Life in Porgy and Bess," musical composed by George Gershwin, libretto by DuBose Heyward and Ira Gershwin]. https://collections.library.yale.edu/catalog/2019639.