Laoutaris, A., I. Madesis, E. P. Benis, and T. J. M. Zouros. “Production of C4+ (2s2p 3,1P) Hollow States in Collisions of 6-18 MeV C4+ (1s2, 1s2s 3S) Mixed-State Beams With Gas Targets”. HNPS Advances in Nuclear Physics, vol. 26, Apr. 2019, pp. 133-8, doi:10.12681/hnps.1808.