TY  - RPRT
TI  - Determination of the angle of internal means of dynamic drilling
AU  - A. Couard
AU  - S. H. Britt
PY  - 1951
DO  - 10.3133/ofr5155c
UR  - https://pubs.usgs.gov/publication/ofr5155C
ID  - ofr5155C
ER  -