1. Andronov, A.A., Vitt, A.A., Khaikin, S.E.: Theory of oscillators, (translated from the Russian by F. Immirzi; translation edited and abridged by W. Fishwick) Pergamon Press, Oxford-New York-Toronto (1966)
2. Anosov, D.V.: Stability of the equilibrium positions in relay systems. Autom. Remote Control 20(2), 130–143 (1959)
3. Brillhart, J.: On the Euler and Bernoulli polynomials. J. Reine Angew. Math. 234, 45–64 (1969)
4. di Bernardo, M., Budd, C.J., Champneys, A.R., Kowalczyk, P.: Piecewise-Smooth Dynamical Systems—Theory and Applications. Applied Mathematical Sciences 163, Springer-Verlag London Ltd., London (2008)
5. Colombo, A., di Bernardo, M., Fossas, E.: Two-fold singularity in nonsmooth electrical systems. In: (ISCAS) Proceedings of 2011 IEEE International Symposium on Circuits and Systems, pp. 2713–2716 (2011)