MLA

Cornell, D. E., and Kansas Pacific Railway Company. Colorado Tourist and Illustrated Guide via the "Golden Belt Route," to the Rocky Mountain Resorts. Ramsey, Millet & Hudson, 1878. https://collections.library.yale.edu/catalog/2031860.

APA, 6th edition

Cornell, D. E., & Company, K. P. R. (1878). Colorado tourist and illustrated guide via the "Golden Belt Route," to the Rocky Mountain resorts [Illustrations, Maps, Promotional literature, Wood engravings]. Ramsey, Millet & Hudson. https://collections.library.yale.edu/catalog/2031860.