Bradley, Raymond S. 1974. ?Secular Changes Of Precipitation In The Rocky Mountains And Adjacent Western States?. Geology And Geography. Geology And Geography. University of Boulder. http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=758390521&sid=2&Fmt=1&clientId=43922&RQT=309&VName=PQD.