This paper was written by Alfred Lotka and published in 1922. In this paper, Lotka argues that the principle of natural selection is a physical principle that applies to all systems that develop out of equilibrium. Consequently, he concluded that this principle should be considered “as a third law of thermodynamics (or a fourth, if the third place be given to the Nernst principle).”
Alfred Lotka. 1922b. Natural selection as a physical principle. Proceedings of the National Academy of Science 8/6: 151–54.