@misc{indiciaeffce19e620f3,
  title = {Delaware River water quality Bristol to Marcus Hook, Pennsylvania, August 1949 to December 1963},
  author = {Walter B. Keighton},
  year = {1965},
  doi = {10.3133/wsp1809o},
  url = {https://pubs.usgs.gov/publication/wsp1809O},
  note = {Source identifier: wsp1809O}
}