Citation:
A. A. Agrachev, R. V. Gamkrelidze, “The Pontryagin Maximum Principle 50 years later”, Dynamical systems: modeling, optimization, and control, Trudy Inst. Mat. i Mekh. UrO RAN, 12, no. 1, 2006, 6–14; Proc. Steklov Inst. Math. (Suppl.), 253, suppl. 1 (2006), S4–S12