Albert Einstein (2013). “Einstein on Politics: His Private Thoughts and Public Stands on Nationalism, Zionism, War, Peace, and the Bomb”, p.475, Princeton University Press
Conversation with George Sewall Boutwell concerning the nomination of Salmon P. Chase to the U.S. Supreme Court, reported by Boutwell in his "Reminiscences of Sixty Years in Public Affairs", vol. 2, (p. 29), 1902.