Vergados, J. D. Division Prof. Dr. Klaus Blaum, MPI for Nuclear Physics, Max Planck Society; CERN Theory Division, Geneva, Switzerland;
http://arxiv.org/abs/arXiv:1107.3296 (Preprint)
http://prc.aps.org/abstract/PRC/v84/i4/e044328 (Publisher version)
Vergados, J. D. (2011). Transition operators entering neutrinoless double electron capture to excited nuclear states. Physical Review C, 84(4): 044328, pp. 1-7. doi:10.1103/PhysRevC.84.044328.