Perturbed pendulum-like motions of a rigid body about a fixed point
  This paper is devoted to a detailed investigation of the perturbed pendulum-like motions of a heavy rigid body about a fixed point. Canonical variables that allow one to simplify the analysis of homoclinic and heteroclinic orbits are introduced. Characteristic properties of perturbed pendulum-like motions of the body in inertial space are studied. A qualitative description of asymptotics of pendulum-like motions in a neighbourhood of split separatrices is given. 
Igor N. Gashenenko
nlin.CD