MLA

Broch, Hermann, 1886-1951. Unidentified pages. Box 38, folder 909. n.d.. https://collections.library.yale.edu/catalog/2044384.

APA, 6th edition

Broch, Hermann, 1886-1951. (["Box 38, folder 909"])(n.d.)[Unidentified pages]. https://collections.library.yale.edu/catalog/2044384.