@misc{indiciae4fd186f13290,
  title = {Report on the operations of the coal-testing plant of the United States Geological Survey at the Louisiana Purchase Exposition, Saint Louis, Missouri, 1904: Part I.--Field work, classification of coals, chemical work},
  author = {E.W. Parker and J.A. Holmes and M. R. Campbell},
  year = {1906},
  doi = {10.3133/pp48},
  url = {https://pubs.usgs.gov/publication/pp48},
  note = {Source identifier: pp48}
}