MLA

McKay, Claude, 1890-1948. Russia. Box 18, folder 599. [ca. 1923]. https://collections.library.yale.edu/catalog/32134908.

APA, 6th edition

McKay, Claude, 1890-1948. (["Box 18, folder 599"])([ca. 1923])[Russia]. https://collections.library.yale.edu/catalog/32134908.