TY  - RPRT
TI  - Geologic map of the Heidelberg 7 1/2-minute Quadrangle, east-central Kentucky
AU  - Douglas F. Black
PY  - 1975
DO  - 10.3133/ofr7573
UR  - https://pubs.usgs.gov/publication/ofr7573
ID  - ofr7573
ER  -