TY  - RPRT
TI  - Self-recording portable soil penetrometer
AU  - Costes, N. C.
AU  - Sturm, R. G.
AU  - Norton, R. H.
AU  - Campbell, G. E.
PY  - 1973
UR  - https://ntrs.nasa.gov/citations/19730010693
ID  - 19730010693
ER  -