MLA

Matthias, Blanche (1887-1983). Mason, Charlotte. Box 2, folder 71. 1923-25, n.d.. https://collections.library.yale.edu/catalog/17170699.

APA, 6th edition

Matthias, Blanche (1887-1983). (["Box 2, folder 71"])(1923-25, n.d.)[Mason, Charlotte]. https://collections.library.yale.edu/catalog/17170699.