MLA

Veĭnbaum, M. E. (Mark Efimovich), 1890-1973. Pozdniakov, Vladimir. Box 6, folder 273. 1970. https://collections.library.yale.edu/catalog/16477267.

APA, 6th edition

Veĭnbaum, M. E. (Mark Efimovich), 1890-1973. (["Box 6, folder 273"])(1970)[Pozdniakov, Vladimir]. https://collections.library.yale.edu/catalog/16477267.