Duncan Farquharson Gregory

Gregory, Duncan Farquharson. 1840. “On the Real Nature of Symbolical Algebra.” Transactions of the Royal Society of Edinburgh 14: 208–216. Reprinted in Ewald (1996, 323–330).

Ewald, William Bragg, ed. 1996. From Kant to Hilbert: A Source Book in the Foundations of Mathematics. Oxford: Oxford University Press.