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2. “The scientific aspects of the Hipparcos space astrometry mission”, 1982, Strasbourg (France) Colloquium, 22-23 Feb. 82, ESA-SP-177.
3. Argue, A.N. et al., 1984, Astron. Astrophys. to be published.
4. Argue, A.N., 1986, IAU Symp. Nr 109, to be published. (*)
5. De Vegt, C. 1986, IAU Symp. Nr 109, to be published.