1. J. P. Blewett, H. A. Liebhafsky, and E. F. Hennelly, “The Vapor Pressure and Rate of Evaporation of Barium Oxide,” J. Chem. Phys. 7: 478, 1939.
2. R. S. Bever, “Diffusion of Barium in an Oxide-Coated Cathode” J. Appl. Phys. 24: 1008, 1953.
3. J. W. Hall et al.,“A Study of Films in Electron Tubes,” Dept. of the Navy, Bureau of Ships, Contract NObsr-81225, General Electric Co., Receiving Tube Dept., Owensboro, Ky.; Final Rept. July 1962.
4. J. W. Hall et al., op. cit.,Second Quarterly Rept. November 1960.
5. J. W. Hall et al., op. cit.,Fifth Quarterly Rept. July 1961.