1. Fliess, M., Lévine, J., Martin, Ph., and Rouchon, P., A Lie-Bäcklund Approach to Equivalence and Flatness of Nonlinear Systems, IEEE Trans. Automat. Control, 1999, vol. 44, no. 5, pp. 922–937
2. Martin, Ph., Murray, R., and Rouchon, P., Flat Systems, Proc. of the 4th Eur. Control Conf. Plenary Lect. and Mini-Courses, Brussels, 1997, pp. 211–264.
3. Bocharov, A.V., Verbovetskii, A.M., Vinogradov, A.M., et al., Simmetrii i zakony sokhraneniya uravnenii matematicheskoi fiziki (Symmetries and Conservation Laws for Equations of Mathematical Physics), Vinogradov, A.M. and Krasil’shchik, I.S., Eds., Moscow, 2005.
4. Krasnoshchechenko, V.I. and Krishchenko, A.P., Nelineinye sistemy: geometricheskie metody analiza i sinteza (Nonlinear Systems: Geometric Methods of Analysis and Synthesis), Moscow, 2005.
5. Chetverikov, V.N., Controllability of Flat Systems, Differ. Uravn., 2007, vol. 43, no. 11, pp. 1518–1527.