Zimmermann, F.J.P. and Conagin, A. 2014. Fitness of 2nd degree polinomials models in fertilizer research. Pesquisa Agropecuaria Brasileira. 21, 9 (Apr. 2014), 971–978. DOI:https://doi.org/10.1590/S1678-3921.pab1986.v21.15012.