1. Born, M., Oppenheimer, R.: Zur Quantentheorie der Molekeln. Ann. Phys.84, 457 (1927)
2. Combes, J.M., Duclos, P.: On the harmonic approximation (to be published)
3. Duclos, P.: On the Harmonic approximation. Thèse du 3-ème cycle, Faculté des sciences, Université de Luminy, Marseille 1974
4. Aventini, P., Combes, J.M., Duclos, P., Grossmann, A., Seiler, R.: On the method of Born and Oppenheimer (to be published)
5. Aventini, P.: On the method of Born and Oppenheimer. Thèse du 3-ème cycle, Faculté des sciences, Université de St. Charles, Marseille 1974