In principle, the SIMBAD bibliographic database is supposed to perform this function. However, in practice the biblio is not utterly complete especially for variable stars. The folks who maintain SIMBAD are aware of this. Perhaps one thing that could be done is to provide citations to them suggesting that they be added to the database. Also, the folks at Sonneberg Observatory maintain a comprehensive variable-star bibliography, which includes even very obscure materials. I do not know the status of this database, but I recall reading that efforts were being made to make it available in machine-readable form. \Brian