1. W. von Bolton: Apparatus for Producing Homogeneous Ductile Bodies from Metals to a Highly Refractory Nature, U.S. Patent No. 925, 798, June 22, 1909.
2. M. Priani: Vacuum, vol. 2, no. 2, April, 1952, p. 159.
3. Weiss and Stimmelmayr: Z. Anorg. Chem., vol. 65, 1909, pp. 323–340
4. W. J. Kroll: Trans. Electrochem. Soc, vol. 78, 1940, p. 35.
5. R. M. Parke and J. L. Ham: The Melting of Molybdenum in the Vacuum Arc, Metals Technology, Tech. Publication no. 2052, vol. 13, 1946, no. 6.