Ultracold bosons with 3-body attractive interactions in an optical lattice E. Fersino, B. A. Malomed, G. Mussardo and A. Trombettoni Eur. Phys. J. B, 68 3 (2009) 417-426 Published online: 18 February 2009 DOI: 10.1140/epjb/e2009-00055-1