On Caspar David Friedrich
Vaughn, William. Friedrich. New York: Phaidon, 2004.
Leighton, John and Colin J. Bailey. Caspar David Friedrich: Winter landscapes. London: National Gallery Publications, 1990.
Koerner, Joseph Leo. Caspar David Friedrich and the Subject of Landscape. New Haven, CT: Yale UP, 1990.

On Hudson River Painters
O’Toole, Judith Hansen. Different Views in Hudson River School Painting. New York: Columbia UP, 2005.
Kornhauser, Elizabeth Mankin, and Amy Ellis. Hudson River School: Masterworks from the Wadsworth Atheneum Museum of Art. New Haven, CT: Yale UP, 2003.
Howat, John K. The Hudson River and its Painters. New York: Viking, 1972.

On Wright Morris
Trachtenberg, Alan, and Ralph Lieberman. Distinctly American: The Photography of Wright Morris. London: Merrell, 2002.
Morris, Wright. God’s Country and My People. New York, Harper & Row, 1968.