Theory of bifurcations of dynamics system on a plane: A. A. Andronov, E. H. leontovich, I. E. Gordon and A. G. Maier, (in Russian). Izdat. Nauka, Moskow, 1967. (English translation, 482 pages, 208 diagrams, 612 × 9case12 in. Price $42.00. Israel Program for Scientific Translations Ltd. New York (1973))