@misc{indiciae7b9072c07e93,
  title = {Automated longwall guidance and control vertical control subsystem, volume 2},
  author = {Griffiths, W. R. and Smirlock, M. and Aplin, J. and Fish, R. B. and Fish, D.},
  year = {1982},
  url = {https://ntrs.nasa.gov/citations/19820010785},
  note = {Source identifier: 19820010785}
}