SAMUELS, G.; VÉLEZ-SANTIAGO, J.; MANZANO, M. A Comparison of Ammonium Sulfate and Urea as Tobacco Fertilizers. The Journal of Agriculture of the University of Puerto Rico, [S. l.], v. 44, n. 1, p. 35–39, 1960. DOI: 10.46429/jaupr.v44i1.12104. Disponível em: https://revistas.upr.edu/index.php/jaupr/article/view/12104. Acesso em: 6 oct. 2022.