@article{219606,
      note = {Potentiometric contours.},
      url = {http://library.usi.edu/record/219606},
      title = {Potentiometric surface of the middle Potomac Aquifer in  Virginia [microform] /},
      publisher = {The Survey ;},
      recid = {219606},
      pages = {maps ;},
      address = {Richmond, Va. :},
}