Timothy H. O'Sullivan, 1871-1874 (survey), (expedition), 4. Grotto Spring, Grand Canon, Colorado River., [Wheeler Survey, Explorations and Surveys West of the 100th Meridian], Stereocard, Etherton Gallery, LL/24716
Timothy H. O'Sullivan 1871-1874 (survey), (expedition) 4. Grotto Spring, Grand Canon, Colorado River. [Wheeler Survey, Explorations and Surveys West of the 100th Meridian]