1. Balbao, A.: 1982, Master's Dissertation, Observat�rio Nacional, Rio de Janeiro, Brazil.
2. Dawson, D. W.: 1977,Publ. Astron. Soc. Pacific 89, 919.
3. Hoffleit, D.: 1964,Catalogue of Bright Stars, Yale University Observatory, New Haven, Connecticut.
4. Hoffleit, D.: 1982,The Bright Star Catalog, Yale University Observatory, New Haven, Connecticut.
5. Kukarkin, B. V., Kholopov, P. N., Efremov, Yu. N., Kukarkina, N. P., Kurochkin, N. E., Medvedeva, G. I., Perova, N. B., Fedorovich, V. P., Frolov, M. S., and Pskovsky, Yu. P.: 1969,General Catalogue of Variable Stars, 3rd ed., Sternberg State Astronomical Institute of the Moscow State University, Moscow.