@misc{indiciae799b96bc2f3c,
  title = {Cosmological fluids as time variables in general relativity.},
  author = {DS Salopek and JM Stewart},
  year = {1993},
  doi = {10.1103/physrevd.47.3235},
  url = {https://pubmed.ncbi.nlm.nih.gov/10015942/},
  note = {Source identifier: 10015942}
}