1. Ando,H. 1983, Publ.Astron.Soc.Japan, 35, 343.
2. Ando,H. 1986, Astron.Astrophys., 163, 97.
3. Baade,D. 1987, in IAU Coll. No.92, Physics of Be stars, ed.A.Slettebak, Cambridge Univ. Press.
4. Struve,O. 1931, Astrophys.J., 73, 94.
5. Willson,L.A. 1986, Publ.Astron.Soc.Pacific, 98, 35.