@misc{indiciae6e2474f5927b,
  title = {The composition of crinoid skeletons},
  author = {F. W. Clarke and W. C. Wheeler},
  year = {1915},
  doi = {10.3133/pp90d},
  url = {https://pubs.usgs.gov/publication/pp90D},
  note = {Source identifier: pp90D}
}