Multiple solutions of the forced double pendulum equation G. Fournier; M. Willem — 1989 Annales de l'I.H.P. Analyse non linéaire
Critical points of convex perturbations of some indefinite quadratic forms and semi-linear boundary value problems at resonance J. Mawhin; M. Willem — 1986 Annales de l'I.H.P. Analyse non linéaire
A PDE approach to certain large deviation problems for systems of parabolic equations L. C. Evans; P. E. Souganidis; G. Fournier; M. Willem — 1989 Annales de l'I.H.P. Analyse non linéaire