Unitarization of the elastic amplitude on the SO(2, 1) group O. N. Soldatenko, A. N. Vall and A. A. Vladimirov Eur. Phys. J. A, 38 1 (2008) 71-76 Published online: 22 September 2008 DOI: 10.1140/epja/i2008-10641-3