"Generic two-variable model of excitability" (2002) Ventura, A.C.; Mindlin, G.B.; Dawson, S.P. Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics. 65(4):7
10.1103/PhysRevE.65.046231
paper_1063651X_v65_n4_p7_Ventura