Sangoi, L. and Silva, P.R.F. da 2014. Comparison of heat units methods and calendar date in predicting development stages of sunflower crop. Pesquisa Agropecuaria Brasileira. 21, 9 (Apr. 2014), 901–908. DOI:https://doi.org/10.1590/S1678-3921.pab1986.v21.14941.