MLA

Ford, Julia Ellsworth, 1859-1950. Dargan, Olive. Box 1, folder 21. 1915-1948. https://collections.library.yale.edu/catalog/17167818.

APA, 6th edition

Ford, Julia Ellsworth, 1859-1950. (["Box 1, folder 21"])(1915-1948)[Dargan, Olive]. https://collections.library.yale.edu/catalog/17167818.