M. Z. Zbořil, S. B. Bauer, M. B. Beck, J. B. Bonn, O. D. Dragoun, J. Jakůbek, J. Žemlička: Ultra-stable implanted Rb-83/Kr-83m electron sources for the energy scale monitoring in the KATRIN experiment. Journal of Instrumentation 8(03), P03009-P03009 (2013). doi:10.1088/1748-0221/8/03/P03009