W. M. Duarte, Álvaro L. Mafra, M. M. Foresti, C. D. Piccolla, and J. A. Almeida, “Potential of olivine melilitite, granite and sienite in the availability of potassium in soils”, Rev. Ciênc. Agrovet., vol. 12, no. 1, pp. 68–77, Jan. 2013.