1. Optimal periodic motions of a controlled system;Tonkov,1977
2. Optimal control limit cycles or what control theory can do to cure a heart attack of cause one;Markus;Lect. Notes Math.,1973
3. Optimal control of periodic solutions;Halanay;Rev. Roum, de Mat. Pures et Appl.,1974
4. The Theory of Oscillations;Zubov,1979
5. Oscillations and Waves;Zubov,1989