Bonnard B., Caillau J.-B., Trelat E., “Second Order Optimality Conditions in the Smooth Case and Applications in Optimal Control”, ESAIM-Control OPtim. Calc. Var., 13:2 (2007), 207–236
В. Ф. Борисов, “Условие Келли и структура лагранжева многообразия в окрестности особой экстремали первого порядка”, Оптимальное управление, СМФН, 19, РУДН, М., 2006, 5–44 ; V. F. Borisov, “Kelley Condition and Structure of Lagrange Manifold in a Neighborhood of a First-Order Singular Extremal”, Journal of Mathematical Sciences, 151:6 (2008), 3431–3472
M. Sigalotti, “Regularity properties of optimal trajectories of single-input control systems in dimension three”, Journal of Mathematical Sciences (New York), 126:6 (2005), 1561
Sigalotti M., “Local Regularity of Optimal Trajectories for Control Problems with General Boundary Conditions”, J. Dyn. Control Syst., 11:1 (2005), 91–123
Agrachev A., Sigalotti M., “On the Local Structure of Optimal Trajectories in R-3”, SIAM J. Control Optim., 42:2 (2003), 513–531
H.J. Sussmann, 1, Proceedings of the 37th IEEE Conference on Decision and Control (Cat. No.98CH36171), 1998, 1
Agrachev A. Sarychev A., “Abnormal Sub-Riemannian Geodesics: Morse Index and Rigidity”, Ann. Inst. Henri Poincare-Anal. Non Lineaire, 13:6 (1996), 635–690
Melikov T., “Recursive Conditions for Optimality of Singular Controls in Systems with Delay”, 322, no. 5, 1992, 843–846
Sarychev A., “High-Order Necessary Conditions of Optimality for Nonlinear Control-Systems”, Syst. Control Lett., 16:5 (1991), 369–378
J.Y. Fourquet, [Proceedings] IECON '90: 16th Annual Conference of IEEE Industrial Electronics Society, 1990, 220