Storing publication reference information

Problem

It would be simplest to store references to articles as an ID number which can be looked up elsewhere. Here are some possibilities in order of preference:

1. DOI or Handle (*)
2. Pubmed ID (**)
3. SICI numbers, if the publisher uses it for a stable URL
4. Biodiversity Heritage Library URL of the article
5. constructed SICI ID (***)

(*) I doubt that there are articles with both a DOI *and* a handle, but if you encounter one, use the DOI. (**) There aren't many articles with Pubmed ID that lack a DOI, but it's possible for pre-1998 pubs. (***) Jim & Hilmar looking into interface to help do this