Leavitt, S. 1982. ?Inference Of Past Atmospheric Delta Carbon-13 And Atmospheric Carbon-Dioxide From Carbon-13/carbon-12 Measurements In Tree Rings?. Geosciences. Geosciences. University of Arizona. http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=752855841&sid=22&Fmt=2&clientId=43922&RQT=309&VName=PQD.