@misc{indiciae4b35201032cd,
  title = {Chapter A6.4. Measurement of pH},
  author = {U. S. Geological Survey},
  year = {2021},
  doi = {10.3133/tm9a6.4},
  url = {https://pubs.usgs.gov/publication/tm9A6.4},
  note = {Source identifier: tm9A6.4}
}