Integrating a family of generic linking tools which can be applied now, e.g. 

• ResearchIndex (automated citation indexing, extracts knowledge from documents, builds link database, NEC, Ref. Lawrence et al., 1999, Digital Libraries and Autonomous Citation Indexing, IEEE Computer)
• Distributed Link Service (places links on documents in original formats, Southampton, Ref. Hitchcock et al., 1997, Citation Linking: Improving Access to Online Journals, Second ACM International Conference on Digital Libraries)
• SFX (database of local resources, including subscription resources, Ghent, Ref. Van de Sompel and Hochstenbach, 1999, Reference Linking in a Hybrid Library Environment, Part 2: SFX, a Generic Linking Solution, D-Lib Magazine)
• SLinkS (links to publishers' holdings, Openly Informatics, Ref. Hellman, 1999, Scholarly Link Specification Framework)