I. Kangro, H. Kalis, A. Gedroics, E. Teirumnieka, and E. Teirumnieks, “On Mathematical Modelling of Metals Distribution in Peat Layers”, MMA, vol. 19, no. 4, pp. 568–588, Sep. 2014, doi: 10.3846/13926292.2014.963718.