MIN-1936-01 Annotated Catalogue of Unpublished Engineering and Geological Reports on Mineral Resources of Colorado MIN-1936-01 Annotated Catalogue of Unpublished Engineering and Geological Reports on Mineral Resources of Colorado
B-19 The Cretaceous Formations of the Northeastern Colorado Plains and the Foothills Formations of North-Central Colorado B-19 The Cretaceous Formations of the Northeastern Colorado Plains and the Foothills Formations of North-Central Colorado