MLA

Dellenbaugh, Frederick Samuel, 1853-1935. Idaho. Box 4, folder 126. n.d.. https://collections.library.yale.edu/catalog/2024907.

APA, 6th edition

Dellenbaugh, Frederick Samuel, 1853-1935. (["Box 4, folder 126"])(n.d.)[Idaho]. https://collections.library.yale.edu/catalog/2024907.