As some of you may know, the Grimm's fairy tales changed between the first and subsequent editions, i.e. they were turned more fitting for children, some of the more crude elements were changed, etc.
Now, I was looking for books that study this kind of evolution of fairy tales. Any ideas on a few good ones?
Jack Zipes is an authority on this sort of thing. His new translation of the First Edition of the Brothers Grimm collection includes a good introduction that will provide you with some of the answers you seek. Zipes has a number of books on the brothers that might help; see also the following:
Breaking the Magic Spell: Radical Theories of Folk and Fairy Tales (Austin: University of Texas Press, 1979).
The Brothers Grimm: From Enchanted Forests to the Modern World (New York: Routledge, 1988).
(Zipes as editor), The Oxford Companion to Fairy Tales (Oxford: University Press, 2015, second edition).
The classic book on folktales is Stith Thompson's, The Folktale (Berkeley: University of California Press, 1977).
For a great access to context - to grapple with early attempts to understand the folktale (and folklore in general), I recommend Alan Dundes, editor, International Folkloristics: Classic Contributions by the Founders of Folklore (New York: Rowan and Littlefield, 1999); Dundes provides essential texts together with his insightful introductions.
In addition to the excellent sources provided by /u/itsallfolklore, I also recommend the following:
The Annotated Grimms' Fairy Tales, ed. Maria Tatar
When Dreams Came True: Classical Fairy Tales and Their Tradition, Jack Zipes
Why Fairy Tales Stick: The Evolution and Relevance of a Genre, Jack Zipes
The Irresistible Fairy Tale: The Cultural and Social History of a Genre, Jack Zipes
Once Upon a Time: A Short History of Fairy Tale, Marina Warner
From the Beast to the Blonde: On Fairy Tales and Their Tellers, Marina Warner
Fairy Tales: A New History, Ruth B Bottigheimer
The following essays/articles may also interest you:
“Cross-Cultural Connections and the Contamination of the Classical Fairy Tale,” Jack Zipes (Found in Norton's The Great Fairy Tale Tradition)
"The Influence of Charles Perrault’s Les Contes de ma Mère l’Oye on German Folklore," Harry Velten (also found in The Great Fairy Tale Tradition)
"The Brothers Grimm as Collectors and Editors of German Folklore," Siegfried Neumann
“Letting Down Rapunzel: Feminism's Effects on Fairy Tales," Angela Smith