1. Single crystal sapphire, The New Value Frontier, Kyocera, 006/003/1008, August 2010, p. 1.
2. D.C.Harris, in: Proceedings of the 10th DoD Electromagnetic Windows Symposium Norfolk, Virginia, 2004.
3. Book, shaped crystal growth, Y.A. Tatarchenko, Kluwer Academics Publisher, 1994.