MLA

Matthias, Blanche (1887-1983). Baldridge, Cyrus LeRoy. Box 1, folder 13-14. 1948-79, n.d.. https://collections.library.yale.edu/catalog/17170694.

APA, 6th edition

Matthias, Blanche (1887-1983). (["Box 1, folder 13-14"])(1948-79, n.d.)[Baldridge, Cyrus LeRoy]. https://collections.library.yale.edu/catalog/17170694.