@misc{indiciaec69b65e9f27e,
  title = {Portland cement materials and industry in the United States},
  author = {Edwin C. Eckel and Ernest Francis Burchard},
  year = {1913},
  doi = {10.3133/b522},
  url = {https://pubs.usgs.gov/publication/b522},
  note = {Source identifier: b522}
}