TY - RPRT TI - Potentiometric surface of the upper Floridan aquifer in the St. Johns River Water Management District and vicinity, Florida, September 1990 AU - R. M. Spechler AU - L. C. Murray AU - L. A. Bradner AU - G. G. Phelps PY - 1991 DO - 10.3133/ofr91190 UR - https://pubs.usgs.gov/publication/ofr91190 ID - ofr91190 ER -