what is aa and what is not.
If you can not find it in writing in AA approved literature according to my sponsor it is not AA, it could be excellent advice, but not AA advice.
In the BB where step 11 is covered there is a paragraph that says:
If circumstances warrant, we ask our wives or friends to join us in morning meditation. If we belong to a religious denomination which requires a definite morning devotion, we attend to that also. If not members of religious bodies, we sometimes select and memorize a few set prayers which emphasize the principles we have been discussing. There are many helpful books also. Suggestions about these may be obtained from one's priest, minister, or rabbi. Be quick to see where religious people are right. Make use of what they offer.
This spells out that other "helpful books" can and should be a part of our AA recovery, AA approved or not.