Jendiroba, Eloisa, and Gil Miguel de Sousa Câmara. “Yield of the Soybean Crop Submitted to Different Sources of Nitrogen”. Pesquisa Agropecuaria Brasileira, vol. 29, no. 8, Aug. 1994, pp. 1201-9, doi:10.1590/S1678-3921.pab1994.v29.4165.