Precise variational calculation of some S-states of Coulomb three-body systems with two identical particles F. Arias de Saavedra, E. Buendía, F. J. Gálvez and A. Sarsa Eur. Phys. J. D, 2 2 (1998) 181-190 Published online: 15 May 1998 DOI: 10.1007/s100530050128