@misc{indiciae2a6d8d180cb2,
  title = {Periodic solutions of a spring-pendulum system.},
  author = {Broucke, R. and Baxa, P. A.},
  year = {1973},
  url = {https://ntrs.nasa.gov/citations/19730060492},
  note = {Source identifier: 19730060492}
}