MLA

Wat, Aleksander, 1900-1967. "Zeszyt 9" (Francja), notebook. Box 33, folder 769. undated. https://collections.library.yale.edu/catalog/2054646.

APA, 6th edition

Wat, Aleksander, 1900-1967. (["Box 33, folder 769"])(undated)["Zeszyt 9" (Francja), notebook]. https://collections.library.yale.edu/catalog/2054646.