1. [1] G. F. Webb, Theory of Nonlinear Age-Dependent Population Dynamics, New York: M. Dekker, 1985. ISBN
9780824772901, 0824772903.
2. [2] A. G. Fredrickson, A mathematical theory of age structure in sexual population: random mating and monogamous marriage models, Math. Biosci., 10 (1971), 117-143.
3. [3] F. C. Hoppensteadt, Mathematical theories of populations, genetics, and epidemics, In CBMS Appl. Math. SIAM, 20, Philadelphia, 1979, 1-71.
4. [4] O. V. Staroverov, Reproduction of the structure of the population and marriages, Ekonomika i matematicheskije metody, (1977), 77-82 (in Russian).
5. [5] K. P. Hadeler, Pair formation with maturation period, J. Math. Biol., 32 (1993), 1-15.