I'm looking for a novel I read around 1995. I read it in Danish, but I think the author might have been German, though I can't be certain. It was likely written for teens or young adults, and I don't think it was a very old book. I would expect it was written in the 80s or early 90s.
I can't remember anything about the plot, except that it was about a werewolf in central Europe. I believe it was Germany but it could be Austria, Switzerland, or even Poland perhaps. The setting was rural - dark forests, castles, small towns - possibly 18th or 19th century, or at least well away from the modern trappings of big cities.
I believe it opened with a quote of some kind, and possibly had drawings of occult signs, magical symbols, or supposed pages from old grimoires. It may have gone into some detail about the nature of werewolves, including possibly the idea that you could become one by drinking water from a pawprint.