Bifurcation analysis of a van der Pol-Duffing circuit with parallel resistor. De Carvalho Braga, Denis, Mello, Luis Fernando, Messias, Marcelo (2009) Mathematical Problems in Engineering
Bounded motions of the dynamical systems described by differential inclusions. Ege, Nihal, Guseinov, Khalik G. (2009) Abstract and Applied Analysis