1. Britton, N. F.: Reaction-diffusion equations and their applications to biology. London: Academic Press 1985
2. Hagedorn, P.: Nonlinear oscillations. Oxford: Clarendon Press 1981
3. Hayashi, C.: Nonlinear oscillations in physical systems. New York: McGraw-Hill 1964
4. Jordan, D. W., Smith, P.: Nonlinear ordinary differential equations. Oxford: Clarendon Press 1979
5. Murray J. D., Oster, G. F.: Cell traction models for generating pattern and form in morphogenesis. J. Math. Biol. 19, 265–279 (1984a)