@article{196647, note = {Cover title.}, author = {Dickinson, Kendell A.,}, url = {http://library.usi.edu/record/196647}, title = {Preliminary chemical and mineralogical analyses of the major volcanic ash beds in the Oligocene Brule Formation, northwestern Nebraska [microform] /}, publisher = {U.S. Dept. of Interior, U.S. Geological Survey ;}, recid = {196647}, pages = {1 v.}, address = {[Reston, Va.] :}, year = {1994}, }