TY - RPRT TI - The difference between the potentiometric surfaces of the Aquia Aquifer of September 1982 and September 1997 in southern Maryland AU - Stephen E. Curtin AU - David C. Andreasen AU - Frederick K. Mack PY - 1999 DO - 10.3133/ofr9981 UR - https://pubs.usgs.gov/publication/ofr9981 ID - ofr9981 ER -