Resonant perturbation theory of decoherence and relaxation of quantum bits. Merkli, M.; Berman, G.P.; Sigal, I.M. — 2010 Advances in Mathematical Physics
Perturbation approach for nuclear magnetic resonance solid-state quantum computation. Berman, G.P.; Kamenev, D.I.; Tsifrinovich, V.I. — 2003 Journal of Applied Mathematics