Biblioscape User Community

One question: I have a couple of references in my database of which the date of publishing is not known. In data freeform, I can add things like 'probably published before 1715', but the problem is that as long as I don't fill anything in in the year-field, these references obviously can't be cross-linked at all. I also can't fill in ???? as these are non integer values for the year field. Can you think of something?

Thanks

Johanna