Jobim, Clóves Cabreira, et al. “Quality of Corn Grain Silage Added With Soybean, Sunflower or Urea”. Pesquisa Agropecuaria Brasileira, vol. 43, no. 5, Oct. 2008, pp. 649-56, doi:10.1590/S1678-3921.pab2008.v43.373.