1. El-Barki, F. A., Ismail, A. I.: Limiting case for the motion of a rigid body about a fixed point in the Newtonian force field. ZAMM75, 821?829 (1995).
2. Malkin, I. G.: Some problems in the theory of nonlinear oscillations. United States Atomic Energy Commission. Technical Information Service, ABC-tr-3766, 1959.
3. Ismail, A. I.: Treating a singular case for a motion of a rigid body in a Newtonian field of force. Arch. Mech.49, 1091?1101 (1997).
4. Arkhangel'skii, Iu. A.: On the algebraic integrals in the problem of motion of a rigid body in a Newtonian field of force. PMM27, 171?175 (1963).
5. Arkhangel'skii, Iu. A.: On a motion of an equilibrated gyroscope in the Newtonian force field. PMM27, 1099?1101 (1963).