Powell, J.W., 1875, Exploration of the Colorado River of the West and its tributaries. Explored in 1869, 1870, 1871, and 1872, under the direction of the Secretary of the Smithsonian Institution: U.S. Congress, 43rd, 1st Session, House Miscellaneous Document 300, 291 p., 2 sheets, scales 1:253,440 and 1:2,534,400.