@misc{indiciae89c83d4c3823,
  title = {Expendable bubble tiltmeter for geophysical monitoring},
  author = {J.A. Westphal and M.A. Carr and W.F. Miller and D. Dzurisin},
  year = {1983},
  doi = {10.1063/1.1137408},
  url = {https://pubs.usgs.gov/publication/70011271},
  note = {Source identifier: 70011271}
}