I know this is a little off-topic but I'm really reluctant to start new topics... Why is there a Chopin Waltz no. 20 in F that doesn't exist in books? And more importantly, what is its level of difficulty? I've read the essay about the waltzes at Piano Society but am still rather puzzled. Has it been confirmed or not? Or at least, in your opinion, is it a Chopin waltz? I'm out to learn the complete set of waltzes in order of difficulty and it would be nice to know. Finally, I noticed it isn't in Bernhard's (all-encompasing) list of difficulty. Upgrade perhaps? Thanks.