Henzinger, Thomas A., and Howard Wong Toi. “Linear Phase-Portrait Approximations for Nonlinear Hybrid Systems.”10.1007/BFb0020961__Hybrid Systems III: Verification and Control, edited by Rajeev Alur et al., vol. 1066, Springer, 1996, pp. 377–88, doi:10.1007/BFb0020961.