【序号】:1 【作者】:1. Thomas K. Rudel 【题名】:Agricultural intensification and changes in cultivated areas, 1970–2005 【期刊】:PNAS 【年卷期】:December 8, 2009 vol. 106 no. 49 20675-20680 【全文链接】: http://www.pnas.org/content/106/49/20675.abstract
【序号】:2 【作者】:1. Alan Grainger 【题名】:Measuring the planet to fill terrestrial data gaps 【期刊】:PNAS 【年卷期】: December 8, 2009 vol. 106 no. 49 20557-20558 【全文链接】: http://www.pnas.org/content/106/49/20557.extract