David Hume, The Philosophical Works of David Hume, Volume 1, Black and Tait, 1826, p. 101.
Jonathan Francis Bennett (2001), Learning from Six Philosophers: Descartes, Spinoza, Leibniz, Locke, Berkeley, Hume, Volume 2, Oxford University Press, ISBN0198250924, p. 53.
Henri Poincaré (1900) "Intuition and Logic in Mathematics" in William Bragg Ewald (ed) From Kant to Hilbert: A Source Book in the Foundations of Mathematics, Volume 2, Oxford University Press, 2007, ISBN0198505361, p. 1015.
