On kaonic hydrogen. Quantum field theoretic and relativistic covariant approach A. N. Ivanov, M. Cargnelli, M. Faber, J. Marton, N. I. Troitskaya and J. Zmeskal Eur. Phys. J. A, 21 1 (2004) 11-28 Published online: 22 June 2004 DOI: 10.1140/epja/i2003-10178-y