1. 1. Abenda S, Gaeta G, Walcher S (eds) (2003) Symmetry and Perturbation
2. 2. Theory??- SPT2002. In: Proceedings of Cala Gonone workshop, 19-26 May 2002. World Scientific, Singapore
3. Abud M, Sartori G (1983) The geometry of spontaneous symmetry breaking. Ann Phys 150:307–372
4. Aleekseevskij DV, Vinogradov AM, Lychagin VV (1991) Basic ideas and concepts of differential geometry. In: Gamkrelidze RV (ed) Encyclopaedia of Mathematical Sciences vol 28 – Geometry I. Springer, Berlin
5. Arnal D, Ben Ammar M, Pinczon G (1984) The Poincaré–Dulac theorem for nonlinear representations of nilpotent Lie algebras. Lett Math Phys 8:467–476