1. Proof of A.N. Kolmogorov's theorem on the preservation of quasiperiodic motions under small perturbations of the Hamiltonian;Arnold;Uspekhi Mat. Nauk,1963
2. The stability of the equilibrium position of a Hamiltonian system of ordinary differential equations in the general elliptic case;Arnold;Dokl. Akad. Nauk USSR,1961
3. On the existence of a third integral of motion;Contopoulos;Astron. J.,1963
4. Resonance cases and small divisors in a third integral of motion II;Contopoulos;Astron. J.,1965