Matthias Kawski, Mathematics of Complexity and Dynamical Systems, 2012, 88
Matthias Kawski, Encyclopedia of Complexity and Systems Science, 2009, 1027
А. И. Третьяк, “О необходимых условиях оптимальности произвольного порядка в задаче быстродействия”, Матем. сб., 132(174):2 (1987), 261–274 ; A. I. Tret'yak, “On necessary conditions of arbitrary order for optimality in a time-optimal problem”, Math. USSR-Sb., 60:1 (1988), 255–268
A. M. Samoilenko, K. Kenzhebaev, V. N. Laptinskii, “Certain iteration methods for the determination of periodic solutions of nonautonomous systems of differential equations”, Ukr Math J, 36:3 (1985), 310