1. "Theory of Oscillations,";A. Andronov;Pergamon Press,1966
2. On the number of limit cycles which appear with the variation of coefficients from an equilibrium position of focus or center type,;N. N. Bautin;Amer. Math. Soc. Translations,1954
3. "Piecewise-Smooth Dynamical Systems. Theory and Applications,";M. di Bernardo;Appl. Math. Sci. Series,2008
4. C. Chicone,;Review in MathSciNet
5. Neuronal networks with gap junctions: A study of piecewise linear planar neuron models,;S. Coombes;SIAM Applied Mathematics,2008