Cite

Jackson, William Henry. Colorado (in Series I)

MLA

Dellenbaugh, Frederick Samuel, 1853-1935. Jackson, William Henry. Colorado (in Series I). Box 7, folder 175. n.d.. https://collections.library.yale.edu/catalog/2018172.

APA, 6th edition

Dellenbaugh, Frederick Samuel, 1853-1935. (["Box 7, folder 175"])(n.d.)[Jackson, William Henry. Colorado (in Series I)]. https://collections.library.yale.edu/catalog/2018172.