Marvin, R.F., Hearn, B.C., Mehnert, H.H., Naeser, C.W., Zartman, R.E., Lindsey, D.A. (1980). Late Cretaceous-Paleocene-Eocene igneous activity in north-central Montana. Isochron/West Bulletin of Isotopic Geochronology, vol. 29, p. 5-26. Edited by: Schilling, John H. Keywords: Cretaceous, Palocene, Eocene north-central Montana