"10.1021/es903385g" . "Energy Efficiency of Conventional, Organic, and Alternative Cropping Systems for Food and Fuel at a Site in the U.S. Midwest"^^ . . "44" . "4006-4011" . "2010"^^ . "10.1021/es903385g" . . . _:genid1 . _:genid1 . _:genid1 . _:genid1 . _:genid1 . _:genid1 . _:genid2 . _:genid2 . _:genid2 . _:genid2 . _:genid2 . _:genid2 . _:genid3 . _:genid3 . _:genid3 . _:genid3 . _:genid3 . _:genid3 . _:genid3 . . . . .