@article{219609,
      recid = {219609},
      title = {Difference between the potentiometric surfaces of the  Aquia Aquifer of ... and ... in southern Maryland  [microform] /},
      publisher = {U.S. Geological Survey ;},
      address = {Towson, Md. :},
      pages = {maps ;},
      note = {Potentiometric contours.},
      url = {http://library.usi.edu/record/219609},
}