Andréa, Mara Mercedes de, et al. “Influence of Repeated Applications of Glyphosate on Its Persistence and Soil Bioactivity”. Pesquisa Agropecuaria Brasileira, vol. 38, no. 11, Nov. 2003, pp. 1329-35, doi:10.1590/S1678-3921.pab2003.v38.6708.