A SU(4)⊗O(3) scheme for nonstrange baryons P. González, J. Vijande, A. Valcarce and H. Garcilazo Eur. Phys. J. A, 31 4 (2007) 515-518 Published online: 26 February 2007 DOI: 10.1140/epja/i2006-10190-9