1. The hardness at high temperatures of some refractory carbides and borides
2. 2L. Kaufman , "Investigation of Boride Compounds for Very High Temperature Applications ," Manlabs, Inc., Cambridge, Mass., Semi-Annual Report No. 1; Contract No. AF33(657)-8635, October1962 .
3. 6B. R. Emrich , "Literature Survey on Synthesis, Properties, and Applications of Selected Boride Compounds ," Directorate of Materials and Processes, Aeronautical Systems Division, Wright-Patterson Air Force Base, Ohio Report No. ASD-TDR-62-873, 122 pp., December1962 .