1. ⁴⁰Ar/³⁹Ar ages of some Challis Volcanic Group rocks and the initiation of Tertiary sedimentary basins in southwestern Montana Author/Creator: M'Gonigle, John W. Publication/Creation: Denver, CO : For sale by the U.S. Geological Survey, Information Services Format: Book Access & Availability: Loading
2. The Río Abajo, Pitahaya, and Daguao Formations in eastern Puerto Rico : a description of three largely volcaniclastic units, which are assigned an early Cretaceous age Author/Creator: M'Gonigle, John W. Publication/Creation: Washington : U.S. Govt. Print. Off, 1977 Format: Book Is Part Of: U.S. Geological Survey bulletin, no. 1434-1439. Access & Availability: Loading