1. Budding E., 1984, Astr Astrophys, 130, 324.
2. Clausen, J V & Gr�nbech B., 1977, Astr Astrophys Suppl Ser, 28, 389.
3. Conover W J, 1971, In: ?Practical Nonparametric Statistics?, p223, Wiley, New York.
4. Doom C., 1984, Astr Astrophys, 138, 101.
5. Duerbeck H W & Karimie M T, 1979, IAU Inf Bull Var Stars, 1617.