@misc{indiciae22c794e8dbcc,
  title = {An improved ultrasonic flowmeter.},
  author = {F E Borgnis and P Frutiger},
  year = {1969},
  doi = {10.1159/000166254},
  url = {https://pubmed.ncbi.nlm.nih.gov/5380966/},
  note = {Source identifier: 5380966}
}