1. Roxin, E., On Generalized Dynamical Systems Defined by Contingent Equations, J. Differ. Equat., 1965, vol. 1, no. 2, pp. 188–205.
2. Kikuchi, N., On Some Fundamental Theorems of Contingent Equations in Connection with the Control Problems, Puhl. RIMS, Kyoto Univ., Ser. A, 1967, vol. 3, pp. 840–844.
3. Krasnosel’skii, M.A. and Pokrovskii, A.V., The Principle of No Bounded Solutions in the Absolute Stability Problem, Dokl. Akad. Nauk SSSR, 1977, vol. 233, no. 3, pp. 293–296.
4. Blagodatskikh, V.I., Teoriya differentsial’nykh vklyuchenii. Ch. 1 (The Theory of Differential Inclusions. Part I), Moscow: Mosk. Gos. Univ., 1979.
5. Filippov, A.F., Differentsial’nye uravneniya s razryvnoi pravoi chast’yu (Differential Equations with Discontinuous Right-Hand Side), Moscow: Nauka, 1985.