MLA

Veĭnbaum, M. E. (Mark Efimovich), 1890-1973. Bunin, Ivan. Box 1, folder 42-45. 1947-53, n.d.. https://collections.library.yale.edu/catalog/16477252.

APA, 6th edition

Veĭnbaum, M. E. (Mark Efimovich), 1890-1973. (["Box 1, folder 42-45"])(1947-53, n.d.)[Bunin, Ivan]. https://collections.library.yale.edu/catalog/16477252.