MLA

Dellenbaugh, Frederick Samuel, 1853-1935. Colorado. Box 3, folder 82. n.d.. https://collections.library.yale.edu/catalog/2018223.

APA, 6th edition

Dellenbaugh, Frederick Samuel, 1853-1935. (["Box 3, folder 82"])(n.d.)[Colorado]. https://collections.library.yale.edu/catalog/2018223.