Isotropic transformations of germs of holomorphic foliations

Given F-omega a germ of holomorphic singular foliation at the origin of C-n defined by an equation omega = 0 (with omega <^> d omega = 0), we are inte rested in describing the group of isotropic transformations of F-omega i.e. , the group of those germs Phi of diffeomorphisms at the origin of C-n that satisfy Phi*omega <^> omega = 0. (C) Elsevier, Paris.