@misc{indiciaef54c47dfa2da,
  title = {Chapter A6. Section 6.4. pH},
  author = {George F. Ritz and J. A. Collins},
  year = {2008},
  doi = {10.3133/twri09a6.4},
  url = {https://pubs.usgs.gov/publication/twri09A6.4},
  note = {Source identifier: twri09A6.4}
}