T. A. Yancey, G. G. Judge, M. E. Bock, Wallace's Weak Mean Square Error Criterion for Testing Linear Restrictions in Regression: A Tighter Bound, Econometrica, Vol. 41, No. 6 (Nov., 1973), pp. 1203-1206

Jeffrey E. Jarrett, An Investigation into the Effects of Independent Investor Relations Firms on Common Stock Prices: Discussion, The Journal of Finance, Vol. 28, No. 2, Papers and Proceedings of the Thirty-First Annual Meeting of the American Finance Association Toronto, Canada, December 28-30, 1972 (May, 1973), pp. 404-405

Econometric models encounter difficulties in handling more than a single kind of output. The absence of data on the flows of intermediate goods makes it impossible to estimate separate production functions for more than one product. Within the unifying framework of the modern theory of cost functions, this paper considers two alternative specifications that can accommodate disaggregation on the output side without requiring data on intermediate goods. The economic implications of these specifications are discussed, and a general specification is proposed in which it is possible to test the two specifications.