Principles of numerical taxonomy / Robert R Sokal and P H A Sneath. Sokal, Robert R. Sneath, Peater H. A. Numerical taxonomy. Biologie. Classification. Taxonomie. 592 SOP Includes indexes. San Francisco : W.H. Freeman, c1963. c1963. 1963 Text xvi, 359 p. : eng A series of books in biology.