1. Arnold, V.I.: Mathematical Methods of Classical Mechanics. Springer, New York (1980)
2. Arnold, V.I.: Reversible systems. In: Nonlinear and Turbulent Processes in Physics, vol. 3, Kiev, 1983. Harwood Academic, Chur, pp. 1161–1174 (1984)
3. Bruno, A.D.: Analytic form of differential equations. Trans. Moscow Math. Soc. 25, 131–288 (1971)
4. Bruno, A.D.: Analytic form of differential equations. Trans. Moscow Math. Soc. 26, 199–239 (1972)
5. Broer, H.W., Huitema, G.B.: A proof of the isoenergetic KAM-theorem from the “ordinary” one. J. Differ. Equ. 90, 52–60 (1991)