9Charles W. Cobb and Paul H. Douglas, A The- ory of Production [ J ] The American Economic Re- view, Vol. 18, No. 1, Supplement, Papers and Proceed- ings of the Fortieth Annual Meeting of the American Eco- nomic Association (Mar. , 1928), pp. 139 - 165.
10Paul H. Douglas, The Cobb- Douglas Produc- tion Function Once Again: Its History, Its Testing, and Some New Empirical Values [ J ] . The Journal of Politi- cal Economy, Vol. 84, No. 5 (Oct., 1976), pp .903.