Hessl, Amy. 2000. ?Aspen: Ecological Processes And Management Eras In Northwestern Wyoming, 1807--1998?. Geology And Geography. Geology And Geography. University of Arizona. http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=731957311&sid=11&Fmt=2&clientId=43922&RQT=309&VName=PQD.