Balfour, A. J. B. (1920). A defence of philosophic doubt: Being an essay on the foundations of belief (A new ed.). Hodder and Stoughton.
Chicago-referens (17:e uppl.)Balfour, Arthur James Balfour. A Defence of Philosophic Doubt: Being an Essay on the Foundations of Belief. A new ed. London: Hodder and Stoughton, 1920.
MLA-referens (8:e uppl.)Balfour, Arthur James Balfour. A Defence of Philosophic Doubt: Being an Essay on the Foundations of Belief. A new ed. Hodder and Stoughton, 1920.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.