@misc{indiciae6b449c013a8b,
  title = {Relativistic collapse to a Schwarzschild sphere.},
  author = {Estabrook, F. B. and Wahlquist, H. D.},
  year = {1967},
  url = {https://ntrs.nasa.gov/citations/19670051709},
  note = {Source identifier: 19670051709}
}