@misc{indiciaebd8a75693278,
  title = {Periodic solutions of second-order nonlinear difference equations containing a small parameter. III - Perturbation theory},
  author = {Mickens, R. E.},
  year = {1986},
  url = {https://ntrs.nasa.gov/citations/19860045049},
  note = {Source identifier: 19860045049}
}