TY  - RPRT
TI  - A borehole geophone leveling device
AU  - Hsi-Ping Liu
AU  - R.E. Westerlund
AU  - Joe B. Fletcher
AU  - R.E. Warrick
PY  - 1986
DO  - 10.3133/ofr86351
UR  - https://pubs.usgs.gov/publication/ofr86351
ID  - ofr86351
ER  -