@misc{indiciaea677812907aa,
  title = {Chemical and physical characteristics of coal and carbonaceous shale samples from the Salt Range coal field, Punjab Province, Pakistan},
  author = {Peter D. Warwick and T. Shakoor and Shahid Javed and S.T.A. Mashhadi and H. Hussain and M. Anwar and M.I. Ghaznavi},
  year = {1990},
  doi = {10.3133/ofr90524},
  url = {https://pubs.usgs.gov/publication/ofr90524},
  note = {Source identifier: ofr90524}
}