A. Laoutaris, 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 Adv Nucl Phys, vol. 26, pp. 133–138, Apr. 2019.