Playing through The Witcher 3 got me interested in all the lore, that mostly find its roots in popular historical folklore like the rusalki and the poĊudnica (Lady Midday). Any books with more information on these sorts of things?
In which countries? I'm interested in Slavic folklore (due to that being what I was mostly exposed to growing up), but a friend is studying Medieval Cornish folklore and folktales so I can recommend some books about that as well.