MLA

Thayer, H. L., and compiler Co. Kansas Pacific Railway Map Showing the Places of Resort in the Rocky Mountains of Colorado / [Cartographic Material]. H.L. Thayer & Co., 0AD. https://collections.library.yale.edu/catalog/33479712.

APA, 6th edition

Thayer, H. L., & Co., compiler. (0 C.E.). Kansas Pacific Railway map showing the places of resort in the Rocky Mountains of Colorado / [cartographic material] [Maps]. H.L. Thayer & Co. https://collections.library.yale.edu/catalog/33479712.