MLA

Berberova, N. (Nina), 1901-1993. Hemlock Society. Box 10, folder 235. 1991. https://collections.library.yale.edu/catalog/16688000.

APA, 6th edition

Berberova, N. (Nina), 1901-1993. (["Box 10, folder 235"])(1991)[Hemlock Society]. https://collections.library.yale.edu/catalog/16688000.