Grüninger, M.Knetter, C.Schmidt, K. P.Uhrig, G. S.2004-12-032004-12-0320012001http://hdl.handle.net/2003/134510.17877/DE290R-12347enThe American Physical SocietyPhysical Review Letters530Fractional and Integer Excitations in Quantum Antiferromagnetic Spin 1/2 Ladders10.1103/PhysRevLett.87.167204article (journal)