1. R. T. Longo, in IEDM Technical Digest (IEEE, 1978), p. 152.
2. R. T. Longo, in IEDM Technical Digest (IEEE, 1980), p. 467.
3. R. T. Longo, E. A. Adler, and L. R. False, in IEDM Technical Digest (IEEE, 1984), p. 318.
4. Electron Emission from Thoriated Tungsten