Cheng, Li. 2005. ?Elevated Atmospheric Carbon Dioxide Impacts Carbon Dynamics In A C(4)-Sorghum-Soil Agroecosystem: An Application Of Stable Carbon Isotopes (Delta Carbon-13) In Tracing The Fate Of Carbon In The Atmosphere-Plant-Soil Ecosystem?. University of Arizona. http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=885700691&sid=10&Fmt=2&clientId=43922&RQT=309&VName=PQD.