A New Map of Texas, Oregon and California (Philadelphia: S. Augustus Mitchell, 1846); image, Library of Congress (loc.gov/item/00561203/ : accessed 30 January 2026).

David Leveson and C. E. Nehru, “Maps, Contours, Profiles, and Gradients,” Brooklyn College –Earth and Environmental Sciences (academic.brooklyn.cuny.edu/geology/grocha/mapcontour/ : accessed 30 January 2026).

United States Geological Survey, Topographic Map: Santa Fe, New Mexico Quadrangle, 30-minute series (1894); image, USGS, topoView (ngmdb.usgs.gov/ht-bin/tv_browse.pl?id=5de8d8c1c82dc5a1d2e4665cec8655dd : accessed 30 January 2026).