dos Santos, H.P. and Reis, E.M. 1994. Crop rotation in Guarapuava. XVII. Energetic efficiency of rotation systems for barley crop, under no-tillage. Pesquisa Agropecuaria Brasileira. 29, 7 (Jul. 1994), 1075–1081. DOI:https://doi.org/10.1590/S1678-3921.pab1994.v29.4150.