Bruce Cotton, Grant Takes Command (Boston, 1968), p. 262

O’Connell, Arms and Men, pp. 198–99

Noll, Civil War, pp. 90–92

Alastair McGrath, The Twilight of Atheism: The Rise and Fall of Disbelief in the Modern World (London and New York), pp. 52–55, 60–66.

James R. Moore, ‘Geologists and Interpreters of Genesis in the Nineteenth Century’, in David C. Lindberg and Ronald L. Numbers, eds, God and Nature: Historical Essays on the Encounter between Christianity and Science (New York, 1986), pp. 341–43