1. Gamma-ray, magnetic, and topographic data for parts of the Colorado Front Range [computer file] Yale Public content 2001. 2002-06-01T04:00:00Z. 2023-02-11T04:46:16Z. Geological Survey (U.S.). The Survey ; For sale by USGS Information Services (Open-File Report Sales). English. Public. Front Range (Colo. and Wyo.).