1. Andronov, A.A., Leontovich, E.A., Gordon, I.I., & Maier, A.G.: Theory of bifurcations of dynamical systems on a plane. Israel Progr. for Sc. Transl. Ltd. 1971.
2. Arnold, V.I.: Lectures on bifurcations and versal familics. In: Russ. Math. Surv. 27, 54–123 (1972).
3. Birkhoff, G.D.: Dynamical systems. In: AMS. Coll. Publ. 9 New York: Amer. Math. Soc. 1927. Reprinted 1966.
4. Borel, A.: Linear algebraic groups. (Notes by H. Bass). Benjamin 1979.
5. Broer, H.W.: Bifurcations of singularities in volume preserving vector fields. Ph.D. thesis, Groningen 1979.