1. Aris, R.: The Mathematical Theory of Diffusion and Reaction in Permeable Catalysts, vols. I and II. Oxford: Oxford University Press 1975
2. Auchmuty, J. F. G.: Lyapunov Methods and Equations of Parabolic Type. (Lect. Notes Math., vol. 322) Berlin Heidelberg New York: Springer 1972
3. Bartlett, M. S.: Deterministic and stochastic models for recurrent epidemics. In: Proc. 3rd Berkeley Symp. Math. Statist. Prob., vol. 4, pp. 81?109. Berkeley Los Angeles: University of California Press 1956
4. Beretta, E., Capasso, V.: On the general structure of epidemic systems. Global asymptotic stability. Comput. Math. Appl. 12A, 677?694 (1986)
5. Beretta, E., Capasso, V., Rinaldi, F.: Global stability results for a generalized Lotka-Volterra system with distributed delays. J. Math. Biol. 26, 661?688 (1988)