1. 1) D. J. Thomas: NASA/CR-2002-211505 (2002).
2. 2) S. R. Levine, E. J. Opila, R. C. Robinson and J. A. Lorincz: NASA/TM-2004-213085 (2004).
3. 3) S. M. Johnson: Presented at 1st Workshop on Science and Technology of UHTC-Based Hot Structure, October, 2008, CIRA, http://www.uhtc.cira.it/presentazioni/2.2_HPartridge_NASA.pdf
4. 4) K. Sakai: Ceramics 24(1989) 526-532.
5. 5) K. Kuwabara: Ceramics 37(2002) 267-271.