TY  - RPRT
TI  - Puerto Rico ground-water quality
AU  - A. L. Zack
AU  - Teresita Rodrigues-Alonso
AU  - Angel Roman-Mas
PY  - 1987
DO  - 10.3133/ofr87749
UR  - https://pubs.usgs.gov/publication/ofr87749
ID  - ofr87749
ER  -