His art teacher in Vienna was Jewish. She made a sketch in 1909 of Adolf Hitler playing chess with another guy who visited him in her apartment. The visitor was Vladimir Lenin. Both men signed the back of her sketch. This sketch was recently sold and has been verified by experts as being real.
https:// www.telegraph.co.uk/news/worldnews/europe/germany/7592013/Rare-sketch-showing-Adolf-Hitler-playing-chess-with-Lenin-to-fetch-thousands.html