1. Ehrlich P. R., Ehrlich A. H., Extinction. The Causes and Consequences of the Disappearance of Species (Random House, New York, 1981).
2. Darwin C., Wallace A. R., J. Proc. Linn. Soc. London Zool.3, 45 (1858).
3. Darwin C., The Origin of Species by Means of Natural Selection (Penguin Classic edition, London, 1985)chap. 4, p. 185.
4. McNaughton S. J., Biodiversity and Ecosystem Function,, Shulze E.-D., Mooney H. A., Eds. (Springer-Verlag, Berlin, 1993).
5. Stauffer R. C., Ed.Charles Darwin's Natural Selection: Being the Second Part of His Big Species Book Written from 1856 to 1858 (Cambridge Univ. Press, London, 1975).