Ellen, with great respect for the intelligence, wisdom, and generosity you so often show here, I have to agree with Aleš. I believe a general principle of data management is that any piece of information has only one primary instance, and all other instances of it are secondary - as references to the primary or backups of it. It has to be done that way to avoid the problems Aleš mentioned, that any change to one instance creates a conflict as to which is correct, especially in a multi-user environment.
The only other case I can think of is when data or databases have to be widely replicated, and are of equal importance. Then, every piece of data has to have a timestamp or version, so that reconciliation can occur when change and conflict happens. I doubt you will want to add versioning to every ref.
Personally, for me, this adds one more reason why I believe that in a multi-user wiki world, separating sources from biography text makes more sense, putting them in a separate 'catalog' with only embedded references in the text. Embedded citations come from the traditional single-author document world, one author control. For me, they are too error prone for our wiki world, of many authors of varying experience and opinions. Certainly, wiki change notifications are helpful for quality control, but a simpler model would make quality control measures less necessary.
