1. Abbott, D.C.: 1978, ApJ
225, 893
2. Abbott, D.C.: 1980, ApJ
242, 1183
3. Baade, D.: 1991, ‘Regular variability of optical lines in Pup’ in D. Baade, ed(s)., ESO Workshop on Rapid Variability of OB-Stars: Nature and Diagnostic Value, ESO:Munich, 21
4. Barker, P.K.: 1986, in A. Slettebak and T.P. Snow, (ed(s)., The Physics of Be Stars (IAU Coll. 92), CUP: Cambridge, 38
5. Barlow, M.J. and Cohen, M.: 1977, ApJ
213, 737