dos Santos, Henrique Pereira, and Erlei Melo Reis. “Crop Rotation in Guarapuava. XVII. Energetic Efficiency of Rotation Systems for Barley Crop, under No-Tillage”. Pesquisa Agropecuaria Brasileira, vol. 29, no. 7, July 1994, pp. 1075-81, doi:10.1590/S1678-3921.pab1994.v29.4150.