Composite asymptotic expansions and turning points of singularly perturbed ordinary differential equations

Augustin Fruchard; Reinhard Schäfke

Comptes Rendus. Mathématique, Volume 348 (2010) p. 1273-1277

On the normal form of a system of differential equations with nilpotent linear part

Mireille Canalis-Durand; Reinhard Schäfke

Comptes Rendus. Mathématique, Volume 336 (2003) p. 129-134