1. Adams, W., Joy, A. H., Humason, M., and Brayton, A.: 1935,Astrophys. J. 81, 285.
2. Allen, C. W.: 1976,Astrophysical Quantities, 4th ed., Athlone Press, London.
3. Al-Naimiy, H. and Budding E.: 1977,Astrophys. Space Sci. 51, 265.
4. Aslan, Z., Asir, A., Engin, S., Tüfekcioglu, Z., and Yilmaz, N.: 1981,Inf. Bull. Var. Stars, No. 1908.
5. Babev, M. B.: 1972,Perem. Zvezdy 18, 389.