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Astron. Astrophys. 319, 637-647 (1997) AcknowledgementsWe wish to thank the referee Dr. F. Spite for many useful suggestions. This research was supported in part by the National Group of Astronomy of the National Council of Research (CNR-GNA) and by the Regional Interuniversity Center for Astrophysics and Cosmology (CIRAC)
© European Southern Observatory (ESO) 1997 Online publication: July 3, 1998 ![]() |