Long before the Internet age, abstracts of the astronomical literature were published annually in the Astronomischer Jahresbericht by the Astronomisches Rechen-Institut in Heidelberg (www.ari.uni-heidelberg.de/publikationen/ajb). The series started in 1899, one year after the first issue of Science Abstracts was published, the precursor of INSPEC (Section 6.1; cf. www.iee.org.uk/publish/inspec/). Abstracts of many papers which originally did not have an English abstract were given in German. Since 1969 its successor, the Astronomy & Astrophysics Abstracts (AAA), published twice a year, have been THE reference work for astronomical bibliography. The slight drawback that it appears about 8 months after the end of its period of literature coverage is compensated by its impressive completeness of ``grey literature'', including conference proceedings, newsletters and observatory publications. Until about 1993, browsing these books was about the only means for bibliographic searches ``without charge'' (except for the cost of the books). In 1993 NASA's ``Astrophysics Data System'' (ADS) Abstract Service with initially 160,000 abstracts became accessible via telnet. After a few months of negotiation about public accessibility outside the US, the service was eventually put on the WWW in early 1994, with abstracts freely accessible to remote users world-wide. Shortly thereafter they turned into (and continue to be) the most popular bibliographic service in astronomy (see [Kurtz et al. (1996), Eichhorn et al. (1998)]).
Upon the announcement during IAU General Assembly XIII (Kyoto, Japan, Aug. 1997) that AAA is likely to stop publication at the end of 1998, some Astronomy librarians compared the completeness of AAA with that of ADS and INSPEC (Section 6.1). The results show that, in particular, information about conference proceedings and observatory reports is missing from ADS and INSPEC. After the demise of AAA, ADS would be the de facto bibliography of astronomy literature, and there is a danger that it will not be as complete as AAA (see www.eso.org/libraries/iau97/libreport.html for a discussion). It would indeed be to the benefit of all astronomers if some day all abstracts from Astronomischer Jahresbericht and AAA (covering 100 years!) became available on the Internet (see Section 6.1 for ARIBIB).
Many bibliographic services in astronomy use a 19-digit reference code or ``refcode'' ([Schmitz et al. (1995)], see e.g. cdsweb.u-strasbg.fr/simbad/refcode.html). They have the advantage of being unique, understandable to the human eye, and may be used directly to resolve the full reference and to see their abstracts on the web. Lists of refcodes are also maintained by NED and ADS (adsabs.harvard.edu/abs_doc/journal_abbr.html). Note, however, that ADS calls them ``bibcodes'', and that for less common bibliographic sources occasionally these may differ from CDS refcodes. Unique bibcodes do not exist as yet for proceedings volumes and monographs, but work is under way in this area.