MLA

Hansen, Bert, 1944-. "Puck's Conception of Mr. Bergh's Steam Flogging Machine.". Box 8, folder 21. 1880 December 8. https://collections.library.yale.edu/catalog/32331493.

APA, 6th edition

Hansen, Bert, 1944-. (["Box 8, folder 21"])(1880 December 8)["Puck's Conception of Mr. Bergh's Steam Flogging Machine."]. https://collections.library.yale.edu/catalog/32331493.