W. Waluyo, N. I. Sinisuka, P. M. Pakpahan, S. Suwarno, and M. A. Djauhari, “Comparison of Eight Month Coastal Polluted Porcelain and Epoxy Resin Outdoor Insulators”, J. Eng. Technol. Sci., vol. 40, no. 2, pp. 122-144, Sep. 2013.