1. Wicksteed’s address to the British Association in 1913. Cf. “The Scope and Method of Political Economy,” reprinted in Wicksteed, P.H., 1910, The Common Sense of Political Economy, Robbins, L. (ed.), Vol. II, pp. 772–796.
2. Russell, B. and Whitehead, A. N., (1925–1927) Principia Math-ematica Cambridge: The Univ. Press (3 Vols., 1910–1913).
3. Later, J. Nicod showed that only a single operator “the stroke function” was necessary.
4. Russell, B. 1956. “Philosophical Analysis” Hibbert Journal. (A Quarterly Review of Religion, Theology, and Philosophy), 54: 321–29.
5. Wicksteed, P. H. An Essay on the Co-ordination of the Laws of Distribution (1894). London: Macmillan.