MLA

Stepun, Fedor, 1884-1965. Frank, Viktor. Box 11, folder 357. 1951-63. https://collections.library.yale.edu/catalog/17335486.

APA, 6th edition

Stepun, Fedor, 1884-1965. (["Box 11, folder 357"])(1951-63)[Frank, Viktor]. https://collections.library.yale.edu/catalog/17335486.