This translation of the second volume of the second edition of the well- known book Theory of Oscillations by Andronov and his collaborators brings to English-speaking readers a full account of the work of these authors. The brilliant translation by Professor Lefschetz of the first edition was a succinct account of the work but was considerably shortened. In so doing some of the flavour and detail of the original work was lost. It is hoped that this translation which, by and large, has not departed too much from the spirit of the Russian edition will be welcomed. There are many practical examples of the most detailed use of the theory, and although the many electrical circuits investigated use thermionic vacuum tubes rather than transistors, the methods demonstrated are of course applicable to all similar types of equations.Translated from the Russian ByF. ImmirziThe Translation Edited and Abridged ByW. Fishwick