MLA

Wat, Aleksander, 1900-1967. "Zeszyt 2," notebook. Box 33, folder 762. undated. https://collections.library.yale.edu/catalog/2054639.

APA, 6th edition

Wat, Aleksander, 1900-1967. (["Box 33, folder 762"])(undated)["Zeszyt 2," notebook]. https://collections.library.yale.edu/catalog/2054639.