MLA

Wat, Aleksander, 1900-1967. "Lektury II," notebook. Box 32, folder 758. undated. https://collections.library.yale.edu/catalog/2054636.

APA, 6th edition

Wat, Aleksander, 1900-1967. (["Box 32, folder 758"])(undated)["Lektury II," notebook]. https://collections.library.yale.edu/catalog/2054636.