Robert B. Barrett and Roger Gibson, F., editors. Perspectives on Quine. Cambridge, Massachusetts: Blackwell. Hacking, Ian. 1991. "A Tradition of Natural Kinds", Philosophical Studies, Vol. 61, No.1/2, (February 1991), pp. 109–126. Kendig, Catherine (ed.), Natural Kinds and Classification in Scientific Practice, Routledge, (Abingdon), 2016. . Putnam, Hilary. 1975. The Meaning of 'Meaning'. in Keith Gunderson, editor. Minnesota Studies in the Philosophy of Science, vol. VII. Minneapolis: University of Minnesota Press. Reprinted in: Quine (1969), Ontological Relativity and Other Essays, Ch. 5, Columbia Univ. Press. Sokal, Robert R. 1974. Classification: Purposes, Principles, Progress, Prospects. Science 185(4157): 1115–1123. External links Natural Kinds, by Alexander Bird and Emma Tobin, in the Stanford Encyclopedia of Philosophy Project Cosmology Modern effort to produce a comprehensive list of major categories for natural kinds Logic Philosophy of science Semantics Ontology