TY  - RPRT
TI  - Phosphate rock resources of the United States
AU  - James Bachelder Cathcart
AU  - Richard Porter Sheldon
AU  - Robert A. Gulbrandsen
PY  - 1984
DO  - 10.3133/cir888
UR  - https://pubs.usgs.gov/publication/cir888
ID  - cir888
ER  -