Straightforward expansion of non-autonomous integrals for quasi-conservative systems with one degree of freedom
N. V. Kovalev

References
1.	A. Kh. Naife, Metody vozmuschenii, Mir, M., 1976, 456 pp.
2.	L. Bobisud, “On The Single First-Order Partial Differential Equation With A Small Parameter”, SIAM Review, 8:4 (1966), 479–-493
3.	A. Puankare, Izbrannye trudy v trëkh tomakh, v. 1, Novye metody nebesnoi mekhaniki, Nauka, M., 1971, 772 pp.
4.	A. Lienard, “Etudes des oscillations entretenues”, Revue generale de l’Electricite, 23 (1928), 901–-912, 946–-954