Peruzzo, Geraldino, Otávio joão F. de Siqueira, and Sírio Wietholter. 1994. “Agronomic Efficiency of Nitrogen Fertilizers for Wheat”. Pesquisa Agropecuaria Brasileira 29 (7):1027-34. https://doi.org/10.1590/S1678-3921.pab1994.v29.4144.