Skaven are bogeymen nobody truly believes in, even though the existence of Beastmen are widely accepted. Unofficial sources seem to say it's mostly because Skaven are highly organized and technical, whereas Beastmen are terrible but rather stupid, barbaric creatures of Chaos.
What official source (sourcebook, website, etc) details comprehensively what an average Empire citizen knows and/or believes of WFRP's monsters?
It's not monster stats — a simple bestiary — I'm looking for. I'm looking for an official source on fluff dealing with in-game people's in-game views.
For the sake of this question let's assume the only books I have are the core books for WFRP1 and WFRP2, but I'm open to sources from any edition including sourcebooks for the strategy game or system-agnostic, world-building publications sanctioned by GW at some point in time.