Holloway, Emory. Walt Whitman: An Interpretation in Narrative. New York & London: Alfred A. Knopf, 1926.
Whitman, Walt. "Letter to Nathaniel Bloom, September 5, 1863." Walt Whitman: The Correspondence 1, (1961): 141-143.
Whitman, Walt. "Letter to Hugo Fritsch, October 8, 1863." Walt Whitman: The Correspondence 1, (1961): 158-160.
Miller, Edwin Haviland. "Introduction." In The Correspondence of Walt Whitman: Volume I, 1842-1867, edited by Edwin Haviland Miller. New York: New York University Press, 1961.