A description of the data in the ADS would be incomplete without a discussion of the interaction between the ADS and the electronic journals. The data available on-line from the journal publishers is an extension of the data in the ADS and vice versa. This interaction is greatly facilitated by the acceptance of the bibliographic code by many journal publishers as a means for accessing their on-line articles.
Access to articles currently on-line at the journal sites through the ADS comprises a significant percent of the on-line journal access (see OVERVIEW). The best model for interaction between the ADS and a journal publisher is the University of Chicago Press (hereafter UCP), publisher of ApJ, ApJL, ApJS, AJ, and PASP. When a new volume appears on-line at UCP, the ADS is notified by email and an SGML header file for each of those articles is simultaneously transferred to our site. The data are parsed and loaded into the system and appropriate links are created. However, prior to this, the UCP has made use of the ADS to build their electronic version through the use of our bibliographic code reference resolver.
Our bibliographic code reference resolver ([Accomazzi et al. 1999]) was developed to provide the capability to automatically parse, identify, and verify citations appearing in astronomical literature. By verifying the existence of a reference through the ADS, journals and conference proceedings editors are able to publish documents containing hyperlinks pointing to stable, unique URLs. Increasingly more journals are linking to the ADS in their reference sections, providing users with the ability to read referenced articles with the click of a mouse button.
During the copy editing phase, UCP editors query the ADS reference resolver and determine if each reference exactly matches a bibliographic code in the ADS. If there is a match, a link to the ADS is established for this entry in their reference section. If there is not a match, one of several scenarios takes place. First, if it is a valid reference not yet included in the ADS (most often the case for "fringe" articles, those peripherally associated with astronomy), our reference resolver captures the information necessary to add it to our database during the next update. Second, if it is a valid reference unable to be parsed by the resolver (sometimes the case for conference proceedings or PhD theses), no action is taken and no link is listed in the reference section. Third, if there is an error in the reference as determined by the reference resolver, the UCP editors may ask for a correction or clarification from the authors.
The last option demonstrates the power of the reference resolver, which has been taught on a journal-by-journal basis how complete the coverage of that journal is in the ADS. Before the implementation of the reference resolver, UCP was able to match 72% of references in ApJ articles (E. Owens, private communication). Early results from the use of the reference resolver show that we are now able to match conference proceedings, so this number should become somewhat larger. It is unlikely that we will ever match more than 90% of references in an article due to references such as "private communication", "in press", and preprints, as well as author errors (see Sect. 8). Our own reference resolving of OCR'd reference lists shows that we can match approximately 86% of references for the best-case scenario.
The ADS provides multiple ways for authors and journal publishers to link to the ADS (see SEARCH). We make every effort to facilitate individuals and organizations linking to us. This is easily done for simple searches such as the verification of a bibliographic code or an author search for a single spelling. However, given the complexity of the system, these automated searches can quickly become complicated. Details for conference proceedings editors or journal publishers who are interested in establishing or improving links to the ADS are available upon request. In particular, those who have individual TeX macros incorporated in their references can use our bibliographic code resolver to facilitate linking to the ADS.
Copyright The European Southern Observatory (ESO)