Optimized δ expansion for relativistic nuclear models G. Krein, R.S. Marques de Carvalho, D.P. Menezes, M. Nielsen and M.B. Pinto Eur. Phys. J. A, 1 1 (1998) 45-53 Published online: 15 January 1998 DOI: 10.1007/s100500050030