The Rebirth of Rapunzel: A Mythic Biography of the Maiden in the Tower by Kate Forsyth was released earlier this spring. I haven't had a chance to explore this yet but I do know it is Forsyth's thesis for her Doctorate of Creative arts on the fairy tale. She has focused much of her studies on the Rapunzel tale and also written a novel, Bitter Greens, inspired by the tale.
So if Rapunzel if your catnip, this is a must read book for you!
Exploring the Rapunzel fairy tale throughout history. Includes research-based exegesis, original translations, poems and articles related to the work.