@misc{indiciae3f3d7c693536,
  title = {Plug cluster engine concept for in-space missions},
  author = {Obrien, C. J. and Aukerman, C. A.},
  year = {1979},
  url = {https://ntrs.nasa.gov/citations/19790054959},
  note = {Source identifier: 19790054959}
}