Herrnstein, R. J. (1974). Formal properties of the matching law. Journal of the Experimental Analysis of Behavior, 21, 159-164.

The matching law implies that any form of behavior approaches an asymptotic frequency as its reinforcement approaches 100 per cent of the total reinforcement being obtained at a given time. This asymptote is formally independent of the kind or quantity of drive or reinforcement associated with the response in question or with any competing response.