MLA

Cassirer, Ernst, 1874-1945. Research notes. Box 45, folder 899. 1936. https://collections.library.yale.edu/catalog/10033807.

APA, 6th edition

Cassirer, Ernst, 1874-1945. (["Box 45, folder 899"])(1936)[Research notes]. https://collections.library.yale.edu/catalog/10033807.