1. R. L. Ackoff and F. E. Emery, On Purposeful Systems (Tavistock, London, 1972; Sov. Radio, Moscow, 1974).
2. V. D. Aleksandrova, Flora Classification. Review of Classification Principles and Classification Systems in Different Geobotanical Schools (Nauka, Leningrad, 1969) [in Russian].
3. V. I. Vasilevich, Statistical Methods in Geobotanics (Nauka, Leningrad, 1969) [in Russian]; V. B. Kovalevskaya, I. B. Pogozhev, and A. P. Pogozheva (Kusurgasheva), “Numerical Methods for Estimating the Proximity Degree of Archeology Monuments by Percentage of Mass Material,” Sov. Arkheol., No. 3, 26–39 (1970).
4. V. N. Kotov, Measuring Theory in Biological Researches (Naukova dumka, Kiev, 1985) [in Russian].
5. B. M. Mirkin and G. S. Rozenberg, Thesaurus of Modern Phytocenology (Nauka, Moscow, 1983) [in Russian].