1. Mlodinow, L., Papanicolaou, N.: Ann. Phys. (N.Y.)128, 314 (1980); Mlodinow, L., Shatz, M.: J. Math. Phys.25, 943 (1984)
2. Bender, C., Mlodinow, L., Papanicolaou, N.: Phys. Rev. A25, 1305 (1982)
3. Mlodinow, L., Papanicolaou, N.: Ann. Phys. (N.Y.)131, 1 (1981)
4. Sukhatme, U., Imbo, T.: Phys. Rev. D28, 418 (1983); Imbo, T., Pagnamenta A., Sukhatme, U.: Phys. Rev. D29, 1669 (1984); For a more complete set of references to work on the 1/N expansion, see: Sukhatme, U., Lauer, B., Imbo, T.: Phys. Rev. D33, 1166 (1986)
5. Nieto, M.M., Gutschick, V.: Phys. Rev. A28, 471 (1983)