MLA

Wat, Aleksander, 1900-1967. "Zeszyt 7," notebook. Box 33, folder 767. undated. https://collections.library.yale.edu/catalog/2054644.

APA, 6th edition

Wat, Aleksander, 1900-1967. (["Box 33, folder 767"])(undated)["Zeszyt 7," notebook]. https://collections.library.yale.edu/catalog/2054644.