John, if you are interested in the theoretical work that seems to have 
been behind these concepts, you might take a look at:

The Economics of Production
Nicholas Georgescu-Roegen
The American Economic Review, Vol. 60, No. 2, Papers and Proceedings of 
the Eighty-second
Annual Meeting of the American Economic Association. (May, 1970), pp. 1-9.

I was fascinated to see G-R's reference to Wicksteed. If G-R is correct 
to cite Wicksteed as the source, it would seem that behind the effort to 
construct a concept that could be subjected to some sort of measurement 
was a general equilibrium theory in which the main driving force was the 
demands for particular goods.

Pat Gunning