Cite

The Rocky Mountains. No. 29.

MLA

Ingersoll, Ernest, 1852-1946, Jackson, William Henry, 1843-1942. The Rocky Mountains. No. 29.. https://collections.library.yale.edu/catalog/2018688.

APA, 6th edition

Ingersoll, Ernest, 1852-1946, & Jackson, William Henry, 1843-1942. [The Rocky Mountains. No. 29.]. https://collections.library.yale.edu/catalog/2018688.