1. Leshchenko, D.D., Shamaev, A.S.: Perturbed rotational motions of a rigid body that are close to regular precession in the Lagrange case. Izv. AN SSSR MTT 22(6), 8–17 (1987)
2. Leshchenko, D.D., Sallam, S.N.: Perturbed rotational motions of a rigid body similar to regular precession. Prikl. Mat. Mekh. 54(2), 183–190 (1990)
3. Ismail, A.I., Amer, T.S., Shaker, M.O.: Perturbed motions of a rotating symmetric gyrostat. Eng. Trans. 46(3–4), 271–289 (1998)
4. Bogoliubov, N.N., Mitropolski, Y.A.: Asymptotic Methods in the Theory of Non-linear Oscillations. Gordon and Breach, New York (1961)
5. Mitropolski, Y.A.: Averaging methods in non-linear mechanics. Int. J. Non-Linear Mech. 2, 69–96 (1967)