Laurent Stolovitch, Freek Verstringe, “Holomorphic Normal Form of Nonlinear Perturbations of Nilpotent Vector Fields”, Regul. Chaotic Dyn., 21:4 (2016), 410–436
Big denominators and analytic normal forms L. Stolovitch International conference "Analysis and Singularities" dedicated to the 75th anniversary of Vladimir Igorevich Arnold December 18, 2012 15:05