@misc{indiciae06ad99cd4cf0,
  title = {Colliding gravitational waves.},
  author = {P Szekeres},
  year = {1970},
  doi = {10.1038/2281183a0},
  url = {https://pubmed.ncbi.nlm.nih.gov/16058854/},
  note = {Source identifier: 16058854}
}