Kliemann, H.J. and Malavolta, E. (2007) “SULPHUR AVAILABILITY IN BRAZILIAN SOILS: AVAILABLE SULPHATE-SULPHUR EVALUATION BY CHEMICAL EXTRACTANTS”, Pesquisa Agropecuária Tropical [Agricultural Research in the Tropics], 23(1), pp. 165–186. doi:10.5216/pat.v23i1.2639.