Tetraquarks in a chiral constituent-quark model J. Vijande, F. Fernández, A. Valcarce and B. Silvestre-Brac Eur. Phys. J. A, 19 3 (2004) 383-389 Published online: 23 December 2003 DOI: 10.1140/epja/i2003-10128-9