Henzinger, Thomas A, and Howard Wong Toi. “Linear Phase-Portrait Approximations for Nonlinear Hybrid Systems.”https://doi.org/10.1007/BFb0020961__In Hybrid Systems III: Verification and Control, edited by Rajeev Alur, Thomas A Henzinger, and Eduardo Sontag, 1066:377–88. Springer, 1996.https://doi.org/10.1007/BFb0020961 .