@misc{indiciae9c6c0705cfcf,
  title = {Circumstances for Pluto-Charon mutual events in 1989},
  author = {Tholen, David J. and Buie, Marc W.},
  year = {1988},
  url = {https://ntrs.nasa.gov/citations/19890034623},
  note = {Source identifier: 19890034623}
}