@misc{indiciae28c866e38f9a,
  title = {A telephone multiline signaling system},
  author = {Toole, P. C. and Belt, J. L. and Goodloe, R. and Leiniger, D. B.},
  year = {1979},
  url = {https://ntrs.nasa.gov/citations/19790000030},
  note = {Source identifier: 19790000030}
}