1. The Helen Planitia region of Venus in four map sheets Author/Creator: Geological Survey (U.S.), issuing body Publication/Creation: Denver, Colorado : For sale by USGS Information Services Resource Type: Map Access & Availability: Loading
2. Historic trail map of the Greeley 1⁰ x 2⁰ quadrangle, Colorado and Wyoming Author/Creator: Geological Survey (U.S.) Publication/Creation: Denver, CO : For sale by Map Distribution Resource Type: Map Access & Availability: Loading
3. Historic trail map of the Lamar 1° x 2° quadrangle, Colorado and Kansas Author/Creator: Scott, Glenn R., 1918-2012 Publication/Creation: Reston, Va. : U.S. Geological Survey, 1995 Resource Type: Map Access & Availability: Loading