According to AA's General Service Office, groups decide what literature is appropriate.
Official AA General Service Office
Conference Approved Literature
We hear it at meetings but what does it mean? Conference Approved Literature.
There is a great deal of valuable literature available. Many AA's don't know about it, probably in part due to misunderstanding of the term "Conference Approved Literature". Some people think that means the only books acceptable to read and sell at a meeting are Conference Approved Literature. But that is a misunderstanding. Really it just means AA can publish it and profit from it. It's saying the content is ok for the AA publishing company to print. It does not mean AA discourages other books or material.
Groups historically have provided pamphlets, step guides and often read from a wide variety of books. Not just the Big Book and Twelve and Twelve.
The following excerpts are from http://hindsfoot.org/confappr.html
Wally P. says that "in the Fall of 1944, a copy of the Washington, DC pamphlet reached Barry C[ollins] -- one of the AA pioneers in Minneapolis. He wrote a letter to the New York headquarters requesting permission to distribute the pamphlet. We talk about 'Conference Approved Literature' today; but this is the way the Fellowship operated back then. This is a letter from Bobbie B[urger], Bill W.'s secretary, printed on 'Alcoholic Foundation' stationary."
November 11, 1944
Dear Barry:
. . . The Washington D.C. pamphlet and the new Cleveland "Sponsorship" pamphlet and a host of others are all local projects. We do not actually approve or disapprove of these local pieces; by that I mean that the Foundation feels each Group is entitled to write up its own "can opener" and let it stand on its own merits. All of them have good points and very few have caused any controversy. But as in all things of a local nature, we keep hands off, either pro or con. I think there must be at least 25 local pamphlets now being used and I've yet to see one that hasn't had some good points. I think it is up to each individual Group whether it wants to use and buy these pamphlets from the Group that puts them out.
Sincerely, Bobbie (Margaret R. Burger)
In November 1950, Bill W. wrote Barry Collins about The Little Red Book, the introduction to the twelve steps which Barry and Ed Webster had been publishing in Minneapolis since 1946 under the sponsorship of the Nicollet group in that city:
The Little Red Book does fill a definite need and has wide circulation. Therefore, its usefulness is unquestioned. AA has a definite place for such a book. Someday I may try to write an introduction book myself which I hope might complement favorably with The Little Red Book. Here at the Foundation we are not policemen; we're a service and AAs are free to read any book they choose.
From Bob Pearson- General Manager of the General Service Office from 1974 to 1984. His story was in the Big Book third edition.
"If you were to ask me what is the greatest danger facing A.A. today, I would have to answer: the growing rigidity -- the increasing demand for absolute answers to nit-picking questions; pressure for G.S.O. to "enforce" our Traditions; screening alcoholics at closed meetings; prohibiting non-Conference-approved literature, i.e., "banning books"; laying more and more rules on groups and members. And in this trend toward rigidity, we are drifting farther and farther away from our co- founders. Bill, in particular, must be spinning in his grave, for he was perhaps the most permissive person I ever met. One of his favorite sayings was, "Every group has the right to be wrong." He was maddeningly tolerant of his critics, and he had absolute faith that faults in A.A. were self-correcting. "
Check out the official AA General Service Office notice on this topic below. AA.org has more info on the topic as well.