MLA

Wolff, Helen, 1906-1994. Invitation. Box 47, folder 1488. 1925 Feb 14. https://collections.library.yale.edu/catalog/2021299.

APA, 6th edition

Wolff, Helen, 1906-1994. (["Box 47, folder 1488"])(1925 Feb 14)[Invitation]. https://collections.library.yale.edu/catalog/2021299.