MLA

Ford, Julia Ellsworth, 1859-1950. Deutsch, Babette. Box 1, folder 24. 1941 April 21. https://collections.library.yale.edu/catalog/17167821.

APA, 6th edition

Ford, Julia Ellsworth, 1859-1950. (["Box 1, folder 24"])(1941 April 21)[Deutsch, Babette]. https://collections.library.yale.edu/catalog/17167821.