MLA

Van Vechten, Carl, 1880-1964. Waters, Ethel, as Petunia Jackson in Cabin in the Sky, musical with music by Vernon Duke, book by Lynn Root, lyrics by John La Touche, and vocal arrangements by Hugh Martin. Box 108 | Folder 1971. 1940 November 17. https://collections.library.yale.edu/catalog/2028470.

APA, 6th edition

Van Vechten, Carl, 1880-1964. (["Box 108 | Folder 1971"])(1940 November 17)[Waters, Ethel, as Petunia Jackson in Cabin in the Sky, musical with music by Vernon Duke, book by Lynn Root, lyrics by John La Touche, and vocal arrangements by Hugh Martin]. https://collections.library.yale.edu/catalog/2028470.