MLA

Luhan, Mabel Dodge, 1879-1962. Loy, Mina. Box 24, folder 664-665. 1913-20, n.d.. https://collections.library.yale.edu/catalog/10000282.

APA, 6th edition

Luhan, Mabel Dodge, 1879-1962. (["Box 24, folder 664-665"])(1913-20, n.d.)[Loy, Mina]. https://collections.library.yale.edu/catalog/10000282.