MLA

Gulʹ, Roman, 1896-1986. Zaitsev, Boris. Box 82, folder 1974. 1963. https://collections.library.yale.edu/catalog/17277463.

APA, 6th edition

Gulʹ, Roman, 1896-1986. (["Box 82, folder 1974"])(1963)[Zaitsev, Boris]. https://collections.library.yale.edu/catalog/17277463.