@misc{indiciaef3c915ce63ae,
  title = {Current concepts for a tracking and data relay satellite system.},
  author = {Clark, G. Q. and Fellerman, K. D. and Schwartz, J. J.},
  year = {1972},
  url = {https://ntrs.nasa.gov/citations/19730030620},
  note = {Source identifier: 19730030620}
}