1. A. A. Andronov, E. A. Leontovich, I. I. Gordon, and A. G. Maier, Qualitative Theory of Second-Order Dynamic Systems (Nauka, Moscow, 1966; J. Wiley, New York, 1973).
2. A. N. Bezdenezhnykh and V. Z. Grines, “Dynamical Properties and Topological Classification of Gradient-like Diffeomorphisms on Two-Dimensional Manifolds. I, II,” Sel. Math. Sov. 11(1), 1–11, 13–17 (1992).
3. R. H. Bing, “Locally Tame Sets Are Tame,” Ann. Math., Ser. 2, 59, 145–158 (1954).
4. C. Bonatti and V. Grines, “Knots as Topological Invariants for Gradient-like Diffeomorphisms of the Sphere S 3,” J. Dyn. Control Syst. 6(4), 579–602 (2000).
5. C. Bonatti, V. Z. Grines, V. S. Medvedev, and E. Pécou, “On Morse-Smale Diffeomorphisms without Heteroclinic Intersections on Three-Manifolds,” Tr. Mat. Inst. im. V.A. Steklova, Ross. Akad. Nauk 236, 66–78 (2002) [Proc. Steklov Inst. Math. 236, 58–69 (2002)].