dos Santos, H. P. and Reis, E. M. (1995) “Crop rotation in Guarapuava, PR Brazil. XVI. Energetic efficiency of rotation systems for wheat, under no-tillage”, Pesquisa Agropecuaria Brasileira, 30(2), pp. 215–222. doi: 10.1590/S1678-3921.pab1995.v30.4295.