TY  - RPRT
TI  - A stratigraphic coding system for data entry into the National Coal Resources Data System
AU  - B.S. Pierce
AU  - B.R. Schachte
AU  - M.F. Johnson
PY  - 1987
DO  - 10.3133/ofr87448
UR  - https://pubs.usgs.gov/publication/ofr87448
ID  - ofr87448
ER  -