B-26 Preliminary Report on the Underground Waters of a Part of Southeastern Colorado B-26 Preliminary Report on the Underground Waters of a Part of Southeastern Colorado
B-20 Preliminary Notes on the Revision of the Geological Map of Eastern Colorado B-20 Preliminary Notes on the Revision of the Geological Map of Eastern 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