Harrison J.E. Geology of the Libby thrust belt of northwestern Montana and its implications to regional tectonics / J.E.Harrison,E.R.Cressman, 1993. - III,42 p. p. - Текст : непосредственный.
Cressman E.R. Reconnaissance stratigraphy of the Prichard Formation (Middle Proterozoic) and the early development of the Belt basin,Washington,Idaho,and Montana / E.R.Cressman, 1989. - 80 p. - Текст : непосредственный.