I've just changed that bit about Caesar being the only ancient source to mention wickermen; not only is it wrong, the source cited doesn't even say that. The relevant text from Strabo, with a reference to the original, is at the page cited. This is a bit of a drive by edit, as I've been reading stuff from Strabo about Celts, and checked in here out of curiosity as to whether anyone else said anything about wicker men. It's fairly clear to me that a lot of what Strabo says about Gaul is derived directly from JC, but I suppose someone would need to find a more reliable authority saying so to clarify that in the article.