@misc{indiciae0e3eb46363ed,
  title = {Vertical-Control Subsystem for Automatic Coal Mining},
  author = {Griffiths, W. R. and Smirlock, M. and Aplin, J. and Fish, R. B. and Fish, D.},
  year = {1984},
  url = {https://ntrs.nasa.gov/citations/19830000659},
  note = {Source identifier: 19830000659}
}