MLA

Speck, William A. (William Alfred), 1864-1928. Commonplace-book. Box 11, folder 400. n.d.. https://collections.library.yale.edu/catalog/16724408.

APA, 6th edition

Speck, William A. (William Alfred), 1864-1928. (["Box 11, folder 400"])(n.d.)[Commonplace-book]. https://collections.library.yale.edu/catalog/16724408.