1. Allen, C. W. 1973, Astrophysical quantities (London: University of London, Athlone Press), 3rd edn.
2. Arenou, F., & Luri, X. 1999, in Harmonizing Cosmic Distance Scales in a Post-HIPPARCOS Era, ed. D. Egret, & A. Heck, ASP Conf. Ser., 167, 13
3. A search for new variable stars in NGC 6231
4. A search for Beta Cephei stars in NGC 6231
5. Photometric monitoring of O-type stars