Somavilla, Lucindo, et al. “Response of Soybean and Corn to Soil Mechanical Intervention and Agricultural Gypsum Application to the Soil Surface”. Semina: Ciências Agrárias, vol. 37, no. 1, Feb. 2016, pp. 95-102, doi:10.5433/1679-0359.2016v37n1p95.