Rahmawati, F., B. Prijamboedi, S. Soepriyanto, and I. Ismu. “Doping Calcia and Yttria into Zirconia Obtained from by Product of Tin Concentrator to Improve Its Ionic Conductivity”. Journal of Mathematical and Fundamental Sciences, vol. 43, no. 1, July 2013, pp. 9-18, doi:10.5614/itbj.sci.2011.43.1.2.