@misc{indiciae3bf7111a9945,
  title = {Digital hum filtering},
  author = {R.W. Knapp and N.L. Anderson},
  year = {1994},
  doi = {10.1016/0098-3004(94)90119-8},
  url = {https://pubs.usgs.gov/publication/70017064},
  note = {Source identifier: 70017064}
}