Does anybody who knows Greek proofread the covers?

I was checking a bibliographic reference yesterday and ran across this:

The accent in σὖν is impossible, and, besides, the word σύν makes no sense in the context. It should be οὖν. The worst of it is that it has ended up in OCLC, the database that drives interlibrary loan, as sun instead of oun—and that's how it ended up that way in the bibliography I was checking.