The DOI, CrossRef, SFX and OpenURL are complementary services that can work together to provide a method for the selection of the most appropriate copy or copies of an article for a particular user - typically those which the user has access rights to.

The SFX server can obtain complete article-level metadata from the CrossRef database. This metadata can then be used to provide a complete set of relevant library-specific services via an SFX menu. The library's proxy server can be used to authenticate off-campus users regardless of the target they connect to.

In cases where a publisher may not support an external article-level link-to syntax, SFX uses CrossRef reverse-lookup services to obtain DOI Names in order to link to article-level. See SFX Target list for publishers who support article-level linking using a DOI Name obtained by SFX from CrossRef.