Radiation reaction, renormalization and Poincaré symmetry. Yaremko, Yurij (2005) SIGMA. Symmetry, Integrability and Geometry: Methods and Applications [electronic only]
Representations of U ( 2 ∞ ) and the value of the fine structure constant. Klink, William H. (2005) SIGMA. Symmetry, Integrability and Geometry: Methods and Applications [electronic only]
Resonances and convergence of perturbation theory for N-body atomic systems in external AC-electric field S. Graffi, V. Grecchi, H. J. Silverstone (1985) Annales de l'I.H.P. Physique théorique