1. Oil and gas investigations, map OM (series). 116. Map of Colorado showing text wells for oil and gas, pipelines, oil and gas fields, and areas of Pre-Cambrian rocks; compiled by Flora K. Walker and N. W. Bass. Scale 10 m.= 1.3 in., scale 1:500,000. Bookmark Corporate/Agency Authors: Geophysical investigations map GP (series). Publisher: Geophysical investigations map GP (series). Date: Edition of 1930, reprinted 1951 SuDoc number: I 10.25/4:11O/sh.1,2