MLA

Matthias, Blanche (1887-1983). O'Keeffe, Georgia. Box 3, folder 76-82. 1926-81, n.d.. https://collections.library.yale.edu/catalog/17170701.

APA, 6th edition

Matthias, Blanche (1887-1983). (["Box 3, folder 76-82"])(1926-81, n.d.)[O'Keeffe, Georgia]. https://collections.library.yale.edu/catalog/17170701.