@misc{indiciae48522fdefc15,
  title = {An approach toward a combined scheme for the petrographic classification of fly ash: Revision and clarification},
  author = {J.C. Hower and I. Suarez-Ruiz and Maria Mastalerz},
  year = {2005},
  doi = {10.1021/ef0498061},
  url = {https://pubs.usgs.gov/publication/70029078},
  note = {Source identifier: 70029078}
}