Soil Microbial Responses to Elevated CO2 and O3 in a Nitrogen-Aggrading Agroecosystem. - Lei Cheng; Booker, Fitzgerald L.; Burkey, Kent O.; Tu, Cong; Shew, H. David; Rufty, Thomas W.; Fiscus, Edwin L.; Deforest, Jared L.; Hu, Shuijin (PLoS ONE, 2011)