TY  - RPRT
TI  - Seismic detection of near-surface cavities
AU  - J. S. Watkins
AU  - R. H. Godson
AU  - Kenneth Watson
PY  - 1967
DO  - 10.3133/pp599a
UR  - https://pubs.usgs.gov/publication/pp599A
ID  - pp599A
ER  -