Clason's sectional map, state of Colorado.
MLA
Co, Clason Map. Clason's Sectional Map, State of Colorado. Clason Map Co., 0AD. https://collections.library.yale.edu/catalog/15818425.
APA, 6th edition
Co, C. M. (0 C.E.). Clason's sectional map, state of Colorado. [Maps]. Clason Map Co., https://collections.library.yale.edu/catalog/15818425.