Bressan, Wellington, et al. “Mycorhizal Fungi and Phosphorus on Growth, Yield and Nutrition of Intercropped Grain Sorghum and Soybean”. Pesquisa Agropecuaria Brasileira, vol. 36, no. 2, Feb. 2001, pp. 315-23, doi:10.1590/S1678-3921.pab2001.v36.6122.