MLA

Wolff, Kurt, 1887-1963. Zur Mühlen, Hermynia von. Box 10, folder 417. 1919-23. https://collections.library.yale.edu/catalog/17271756.

APA, 6th edition

Wolff, Kurt, 1887-1963. (["Box 10, folder 417"])(1919-23)[Zur Mühlen, Hermynia von]. https://collections.library.yale.edu/catalog/17271756.