1. Agrachev, A.A.: Topology of quadratic maps and hessians of smooth maps. Itogi nauki. VINITI. Algebra. Topologiya. Geometriya 26, 85–124 (1988); Translated in J. Soviet Math. 49(3), 990-1013 (1990)
2. Agrachev, A.A., Sachkov, Y.: Control theory from the geometric viewpoint. Vol. 87, Encyclopaedia of Mathematical Sciences. Springer-Verlag, Berlin Heidelberg New York (2004)
3. Agrachev, A.A.: Geometry of optimal control problems and Hamiltonian systems. Nonlinear and optimal control theory, 1-59, Lecture Notes in Math., 1932. Springer-Verlag, Berlin Heidelberg (2008)
4. Agrachev, A., Barilari, D., Boscain, U.: Introduction to Riemannian and sub-Riemannian geometry (Lecture Notes),
http://people.sissa.it/agrachev/agrachev_files/notes.html
(2012)
5. Agrachev, A.A., Gamkrelidze, R.V.: Quadratic maps and smooth vector valued functions; Euler Characteristics of level sets. Itogi nauki