http://www.nps.gov/history/history/online_books/romo/buchholtz/chap2.htm (http://www.nps.gov/history/history/online_books/romo/buchholtz/chap2.htm)
http://www.thegeozone.com/treasure/colorado/history/co_history2.jsp (http://www.thegeozone.com/treasure/colorado/history/co_history2.jsp)
http://en.wikipedia.org/wiki/Rocky_Mountains (http://en.wikipedia.org/wiki/Rocky_Mountains)
http://www.phsbc.info/boggs.htm (http://www.phsbc.info/boggs.htm)
http://denver.yourhub.com/Story.aspx?contentID=57815 (http://denver.yourhub.com/Story.aspx?contentID=57815)
http://www.over-land.com/trwestmid.html (http://www.over-land.com/trwestmid.html)
http://www.loc.gov/exhibits/lewisandclark/lewis-after.html (http://www.loc.gov/exhibits/lewisandclark/lewis-after.html)