MLA

Byron, Robert, 1905-1941. India (largely New Delhi). Box 49, folder 713-726. circa 1929. https://collections.library.yale.edu/catalog/2034159.

APA, 6th edition

Byron, Robert, 1905-1941. (["Box 49, folder 713-726"])(circa 1929)[India (largely New Delhi)]. https://collections.library.yale.edu/catalog/2034159.