1. Winfree, A. T. The Geometry of Biological Time (Springer, Berlin, 1980).
2. Glass, L. & Mackey, M. C. From Clocks to Chaos: The Rhythms of Life. (Princeton University Press, Princeton, NJ, 1988).
3. Rinzel, J. & Ermentrout, B. Analysis of neural excitability and oscillations. In Koch, C. & Segev, I. (eds) Methods of Neuronal Modeling, 251–292 (MIT Press, Cambridge, 1998).
4. Canavier, C. C. Phase response curve. Scholarpedia 1, 1332 (2006).
5. Izhikevich, E. The Dynamical Systems in Neuroscience: Geometry of Excitability and Bursting (The MIT Press, 2007).