Georgia O'Keeffe, Sarah Greenough, Alfred Stieglitz (2011). “My Faraway One: Selected Letters of Georgia O'Keeffe and Alfred Stieglitz: Volume One, 1915-1933”, p.568, Yale University Press
"An Additional Number of Letters to the Republican". Letters by the Federal Farmer (pseudonym of Richard Henry Lee), Letter XVIII, teachingamericanhistory.org. January 25, 1988.
Samuel R. Delany (2014). “The American Shore: Meditations on a Tale of Science Fiction by Thomas M. Disch—“Angouleme””, p.150, Wesleyan University Press