A while back I
wrote about a self-publicising vanity author. One of
the details I'd liked to have note was the complete (or near-complete)
absence of his books in public library catalogues, but it's almost
impossible to actually find a way to cite a "negative search" much
less a positive result...
Indeed, that would end up being OR - quite simple OR, but OR all the
same. It's annoying when you know something that apparently no-one has
published, but there isn't much we can do about it. (Unless you happen
to be an expert on the subject and can publish it yourself)