1. Gruver SP.“Magnesia-Spinel Refractory Brick”, Patent no. 6261983, United States, July 2001.
2. Itoh K, Takemoto M, Ogata M. “Recent Trends in Cement Kiln Refractories”, Shinagawa Technical Report, Japan 2000.
3. Magnesia–hercynite bricks: an innovative burnt basic refractory;Buchebner;UNITECR Berlin,1999
4. Performance of new chrome free magnesia bricks in precalciner kilns;Nievoll,1999
5. Tsuchinari A, Osaki H, Okamoto H, Yamamoto T. “Chrome-Free Brick”, Patent no. 5559064, United States, September 1996.