1. P. R. Lubicki and B. W. Koo, U.S. Patent No. 8,604,449 (1 July 2010).
2. On the development of a 15 mA direct current H− multicusp source
3. A CW radiofrequency ion source for production of negative hydrogen ion beams for cyclotrons
4. The extraction of negative carbon ions from a volume cusp ion source
5. S. Melanson, M. Dehnel, H. McDonald, C. Philpott, and D. Potkins, “H−, D−, C2: A Comparison of RF and Filament Powered Volume-Cusp Ion Sources.” In 8th Int. Particle Accelerator Conf. (IPAC’17), Copenhagen, Denmark, 14-19 May 2017, (JACOW 2017), pp. 1685–1687.