Cite

"Dr. Koch's Discovery."

MLA

Hansen, Bert, 1944-. "Dr. Koch's Discovery.". Box 13, folder 23. 1891 January 6. https://collections.library.yale.edu/catalog/32332233.

APA, 6th edition

Hansen, Bert, 1944-. (["Box 13, folder 23"])(1891 January 6)["Dr. Koch's Discovery."]. https://collections.library.yale.edu/catalog/32332233.