Here is a letter from JD Salinger to a producer about make Catcher in the Rye into a film. Notice the final line about all the other letters her has read on the matter:
http://collider.com/catcher-in-the-rye-movie-rejection-jd-salinger/147583/
Here is a collection of Salinger sources:
http://www.literaryhistory.com/20thC/Salinger.htm
