Mylarappa, M., et al. “Cyclic Voltammetry and Electrochemical Impedance Spectral Properties of MnO2 Obtained by Waste Discarded Batteries Using Eco-Friendly Leaching Materials”. Asian Journal of Chemistry, vol. 29, no. 9, July 2017, pp. 2016-24, doi:10.14233/ajchem.2017.20743.