(80.5): J.F. Wyart, V. Kaufman and J. Sugar, Physica Scripta, Sweden, 1980, 22, 389-96.

(83.3): Z.B. Goldschmidt, Phys. Rev. A, U.S.A., 1983, 27, 740-53.

(84.5): C.H.H. Van Deurzen, K. Rajnak and J.G. Conway, J. opt. Soc. Am. B, 1984, 1, 45-7.