Samuels G, Vélez-Santiago J, Manzano M. A Comparison of Ammonium Sulfate and Urea as Tobacco Fertilizers. JAUPR [Internet]. 1960 Jan. 1 [cited 2024 Dec. 22];44(1):35-9. Available from: https://revistas.upr.edu/index.php/jaupr/article/view/12104