@misc{indiciae71109e0a4903,
  title = {Phosphorite and other apatite-bearing sedimentary rocks in the Precambrian of northern Michigan},
  author = {William F. Cannon and J. S. Klasner},
  year = {1976},
  doi = {10.3133/cir746},
  url = {https://pubs.usgs.gov/publication/cir746},
  note = {Source identifier: cir746}
}