Herrera Coello, N., Y. Barceló Martín, and A. García Rodríguez. “Study of the Good Nutritional Conditions for the Production of Biological Fertilizer to Leave of Azotobacter”. Centro Azúcar Journal, vol. 35, no. 2, Apr. 2008, http://centroazucar.uclv.edu.cu/index.php/centro_azucar/article/view/503.