@misc{indiciae140125dfccdb,
  title = {Density gradient centrifugation: Application to the separation of macerals of type I, II, and III sedimentary organic matter},
  author = {B.A. Stankiewicz and M.A. Kruge and J.C. Crelling and G.L. Salmon},
  year = {1994},
  url = {https://pubs.usgs.gov/publication/70017343},
  note = {Source identifier: 70017343}
}