Stafilov, T. “Corrections of the Methods for Manganese Determination in Waste Waters by UV-VIS Spectrophotometry and Atomic Absorption Spectrometry and Investigation of the Possibility for Its Precipitation”. Macedonian Journal of Ecology and Environment, vol. 2, no. 1, Aug. 1994, pp. 91-99, http://mjee.org.mk/index.php/mjee/article/view/19.