Translating Wookie

Well if I can contact my friend ( she is very into the languages for star trek & star wars ) she should be able to give me some more insight, into which book the mention of the written language was. But logicly it makes sense that they would have one, Wookies are an advanced society & you would have some kind of written language, ceremonial or mundane or it could be a mathematic one ( possibly ) ...sorry now I am starting to go off on tangents..my bad just a thought