J.L.W.S. The Special One wrote:
I agree about systemic bias caused by requiring that sources be in English (or whatever language the Wikipedia is in).
I'm pretty sure there isn't any such requirement. Now if it's a subject on which tons of information *is* available in English, gratuitously referencing non-English material is frowned on, but on more obscure subjects non-English references are perfectly fine. I've written dozens of articles myself that reference non-English books and encyclopedias, and nobody's ever complained about that, so I'd be surprised if it were against some sort of policy.
-Mark