TY  - RPRT
TI  - The national coal-resources data system of the U.S. geological survey
AU  - M.D. Carter
PY  - 1976
DO  - 10.1016/0098-3004(76)90062-5
UR  - https://pubs.usgs.gov/publication/70010350
ID  - 70010350
ER  -