@article{198862, note = {Distributed to depository libraries in microfiche.}, author = {Mack, Frederick K.}, url = {http://library.usi.edu/record/198862}, title = {The difference between the potentiometric surfaces of the Magothy Aquifer of September 1975 and September 1990 in southern Maryland [microform] /}, publisher = {The Survey ;}, recid = {198862}, pages = {1 map ;}, address = {Towson, Md. :}, year = {1992}, }