@misc{indiciae8c1d4fdaf1ad,
  title = {Microbial contributions to the Precambrian Earth},
  author = {Margulis, L. and Bermudes, D. and Obar, R.},
  year = {1986},
  url = {https://ntrs.nasa.gov/citations/19860017427},
  note = {Source identifier: 19860017427}
}