Alves, Francisco Gleyson da Silveira, et al. “Agronomic and Nutritional Responses of Carajas Elephant Grass Fertilized With Protected and Non-Protected Urea”. Semina: Ciências Agrárias, vol. 39, no. 5, Aug. 2018, pp. 2181-94, doi:10.5433/1679-0359.2018v39n5p2181.