MLA

Hansen, Bert, 1944-. "M. Pasteur, the French chemist and biologist, who recently celebrated his seventieth birthday.". Box 2, folder 38. 1893 January 12. https://collections.library.yale.edu/catalog/32329335.

APA, 6th edition

Hansen, Bert, 1944-. (["Box 2, folder 38"])(1893 January 12)["M. Pasteur, the French chemist and biologist, who recently celebrated his seventieth birthday."]. https://collections.library.yale.edu/catalog/32329335.