TY  - RPRT
TI  - Guidelines for logging, describing, and sampling cores and cuttings of coal and associated rocks at the drill site
AU  - Robert G. Hobbs
PY  - 1979
DO  - 10.3133/ofr791522
UR  - https://pubs.usgs.gov/publication/ofr791522
ID  - ofr791522
ER  -