Macedo, Walfredo. “The Effect of Sources and Levels of Phosphorus and Lime for Forrage Pasture Fertilization in Rio Grande Do Sul”. Pesquisa Agropecuaria Brasileira, vol. 20, no. 6, Apr. 2014, pp. 643-57, doi:10.1590/S1678-3921.pab1985.v20.15702.