TY  - RPRT
TI  - Stratigraphy and geologic history of the Montana group and equivalent rocks, Montana, Wyoming, and North and South Dakota
AU  - James R. Gill
AU  - William Aubrey Cobban
PY  - 1973
DO  - 10.3133/pp776
UR  - https://pubs.usgs.gov/publication/pp776
ID  - pp776
ER  -