1. Babel, J. 1998, in Variable & Non-spherical Stellar Winds, ed. B. Wolf, O. Stahl, & A. Fullerton, IAU Colloq., No. 169 (Springer, Heidelberg), 187
2. Babel, J., & Montmerle, T. 1996, in Hydrogen Deficient Stars, ed. C. Jeffery, & U. Heber, ASP, San Francisco, 96, 189
3. On the Periodic X-Ray Emission from θ[TSUP]1[/TSUP] Orionis C
4. Balona, L. A. 2000, in The Be Phenomenon in Early-Type Stars, ed. M. A. Smith, H. F. Henrichs, & J. Fabregat, ASP Conf. Ser., 214, 1