Salles, Pedro Afonso Almeida de, and José Otávio Neto Gonçalves. “Economic Efficiency of Nitrogen in Cultivated Pastures”. Pesquisa Agropecuaria Brasileira, vol. 16, no. 1, Apr. 2014, pp. 27-31, doi:10.1590/S1678-3921.pab1981.v16.16464.