Original artwork: Joseph Bartholomew Kidd, 1830–31. Available through Creative Commons.
William J. Beecher, Duck Hawk after Widgeon, 1940. Available through the Smithsonian American Art Museum.
Original artwork: William Trost, A Rocky Coast, 1877. Available through the Creative Commons.
Frederic Edwin Church, Alpine Scene in Thunderstorm, 1868. Available through Creative Commons.
Robert S Duncanson, Waterfall on Mont Morency, 1894. Freely available through Creative Commons.
Original Artwork: William J. Beecher, Duck Hawk after Widgeon, 1940. Available through the Smithsonian American Art Museum.
Original artwork: Albert Bierstadt, Among the Sierra Nevada, California, 1868. Available through the Smithsonian American Art Museum.