TY  - RPRT
TI  - Coal resources of Colorado, a progress report, January 1, 1953
AU  - Frank Darwyn Spencer
AU  - Margaret Isabelle Erwin
PY  - 1953
DO  - 10.3133/cir258
UR  - https://pubs.usgs.gov/publication/cir258
ID  - cir258
ER  -