@misc{indiciae30445b8c16b0,
  title = {Periodic solutions of second-order nonlinear difference equations containing a small parameter. IV - Multi-discrete time method},
  author = {Mickens, Ronald E.},
  year = {1987},
  url = {https://ntrs.nasa.gov/citations/19880033323},
  note = {Source identifier: 19880033323}
}