Defregapa ( englavon Old Faithful ) tir trutca lumkirafa gu 49.5 × 34.9 cm-, i puntalingeks keve eluxa keve stama skuyun gan Albert Bierstadtamerikaf lingesik bak 1881.
(en) American paradise: the world of the Hudson River school, New York, The Metropolitan Museum of Art, 1987, ISBN 9780870994968
(en) Anderson, Nancy K. Albert Bierstadt, Art & Enterprise, Hudson Hills Press, Inc., New York, 1990.
(en) Barringer, Tim and Wilton, Andrew. American Sublime: Landscape Painting in the United States 1820-1880, Princeton University Press, 2002. ISBN 0-691-09670-8
(en) Hendricks, Gordon. Albert Bierstadt, Painter of the American West, Harrison House/Harry N. Abrams, Inc., New York 1988.
(en) Miller, Angela. Albert Bierstadt, Landscape Aesthetics, and the Meanings of the West in the Civil War Era. Art Institute of Chicago Museum Studies, 27, Chicago.
