00498nam a2200169Ia 4500008004100000020001500041082001700056100002200073245008700095260004000182300000800222650001400230650002000244653002300264653002100287653002000308170901s1978    xx            000 0 und d  a0470264276  a338.16bO21O  aOelhaf, Robert C. 0aOrganic AgriculturebEconomic and Ecological Comparisons with Conventional Methods  aNew YorkbJohn Wiley and Sonsc1978  a271  aEconomics  aSocial sciences  aEcological aspects  aEconomic aspects  aOrganic farming