@misc{indiciae26adc5943a08,
  title = {Slope angle distribution of coal beds with strippable reserves},
  author = {Kenneth John Englund and M. J. Bergin and M.D. Carter and C.R. Meissner and J.B. Roen},
  year = {1977},
  doi = {10.3133/ofr77213},
  url = {https://pubs.usgs.gov/publication/ofr77213},
  note = {Source identifier: ofr77213}
}