Johnson, Ross B. 1919- Coal resources of the Trinidad coal field in Huerfano and Las Animas counties, Colorado / by Ross B. Johnson. -- Washington : United States Government Printing Office, 1961 - P. 130-180 + map. -- (Geological Survey Bulletin ; 1112-E). Subjects--Topical Terms: ColoradoGeología Universal Decimal Class. No.: 55(788)