Ren, W., Tian, HQ, Xu, XF, Liu ML, Lu CQ, Chen GS, Mellio J., Reilly John, Liu, JY (2011) Spatial and temporal patterns of CO2 and CH4 fluxes in China’s croplands in response to multifactor environmental changes, Tellus B DOI: 10.1111/j.1600-0889.2010.00522.x