MLA

Berberova, N. (Nina), 1901-1993. Smakov, Gennady. Box 19, folder 517-518. 1970-87, n.d.. https://collections.library.yale.edu/catalog/17305291.

APA, 6th edition

Berberova, N. (Nina), 1901-1993. (["Box 19, folder 517-518"])(1970-87, n.d.)[Smakov, Gennady]. https://collections.library.yale.edu/catalog/17305291.