MLA

Berberova, N. (Nina), 1901-1993. Barker, Murl. Box 53, folder 1207-1208. 1973-89, n.d.. https://collections.library.yale.edu/catalog/10454164.

APA, 6th edition

Berberova, N. (Nina), 1901-1993. (["Box 53, folder 1207-1208"])(1973-89, n.d.)[Barker, Murl]. https://collections.library.yale.edu/catalog/10454164.