1. Allen, R.G.D. (1932). Decreasing costs: a mathematical note. Economic Journal. 323 et seq.
2. Amoroso, L. (1930). La curva statica di offerta (published in English as: The Static Supply Curve). Giornale degli economisti, 2.
3. Cassel, G. (1967). The Theory of Social Economy, translated by S.L. Barron, New revised edition, New York, Augustus M. Kelley Publishers, (coll. Reprints of Economics Classics, VIII+689 pages.): 11 et seq.
4. Harrod, R. F. (1931). The law of decreasing costs, Economic Journal, vol. 41, No. 164, December: 566–576.
5. Marshall, A. (1890). Handbuch der Volkswirtschaftslehre (published in English as: Principles of Economics), vol. 1, Book V.