Nikolaenko, S.A., I.V. Ilyenko, A.I. Zubarev, L.A. Shapiro, A. Muschweck, and U. Lohbauer. 2015. “Hardness of Dental Ceramics”. Clinical Dentistry (Russia), no. 1 (March). Moscow, Russia:10—14. http://www.kstom.ru/ks/article/view/0073-02.