121b. East from Gunsight Pass.
MLA
McClintock, Walter, 1870-1949. 121b. East from Gunsight Pass.. Box 71, folder 3997. 1905 1941. https://collections.library.yale.edu/catalog/2010611.
APA, 6th edition
McClintock, Walter, 1870-1949. (["Box 71, folder 3997"])(1905 1941)[121b. East from Gunsight Pass.]. https://collections.library.yale.edu/catalog/2010611.