MLA

Rzhevskiĭ, Leonid, 1905-1986. Pregel', Sofiia. Box 10, folder 207. 1953. https://collections.library.yale.edu/catalog/16603933.

APA, 6th edition

Rzhevskiĭ, Leonid, 1905-1986. (["Box 10, folder 207"])(1953)[Pregel', Sofiia]. https://collections.library.yale.edu/catalog/16603933.