MLA

Matthias, Blanche (1887-1983). Baldridge, Cyrus LeRoy. Box 4, folder 127-28. 1968-77, n.d.. https://collections.library.yale.edu/catalog/17170705.

APA, 6th edition

Matthias, Blanche (1887-1983). (["Box 4, folder 127-28"])(1968-77, n.d.)[Baldridge, Cyrus LeRoy]. https://collections.library.yale.edu/catalog/17170705.