M. V. Reboucas, A. R. C. G. Massa, and M. . Vinicio Assis, “Analysis of effluent from caustic treatment plants: Improvement of accuracy in the simultaneous potentiometric determination of sulfide and mercaptide ions”, CT&F Cienc. Tecnol. Futuro, vol. 3, no. 2, pp. 163–170, Dec. 2006.