@article{Maciejewski:2005,
  author  = "A. Maciejewski and W. Radzki and S. Rybicki",
  title   = "Periodic trajectories near degenerate equilibria in the Henon-Heiles and Yang-Mills Hamiltonian systems",
  journal = "Journal of Dynamics and Differential Equations",
  volume  = "Vol. 17",
  number  = "no 3",
  pages   = "475--488",
  year    = "2005",
}