B121: S. Ouaskit, B. Farizon-Mazuy, M. Farizon, M. J. Gaillard, E. Gerlic, M. Stern, A. Clouvas, A. Katsanos, "Fast negative helium ions produced by double electron capture in single He+ - He collisions", Physical Review A48, 1204-1208 (1993). [10.1103/physreva.48.1204]