1. P.-F. Verhulst, Corresp. Math. Phys. 10, 113 (1838).
2. P.-F. Verhulst, Nouv. Mem. Acad. R. Sci. B.–Lett. Brux. 18, 1 (1845).
3. P.-F. Verhulst, Mem. Acad. R. Sci. Lett. B.–Arts Belg. 20, 142 (1847).
4. Yu. Loskutov and A. S. Mihailov, Introduction to Synergetics (Science, Moscow, 1990).
5. H. Haken, Synergetics. Introduction and Advanced Topics (Springer, 2004).