The only qualification needed to write a book about poker is the ability to get somebody to publish it. There is a lot of junk available written by people without a clue about how to play winning poker. All of these however present useful information that should get a reader thinking. Do not just passively accept what any writer presents.
Parrots are no threat at a poker table.
Click here for a page of the best poker movies available, plus more books. The Theory of Poker David Sklansky. A somewhat dated but excellent introduction to the game. Ray is one of the most successful players around. The advice here is geared toward higher limit play, but if a reader understands that and adapts to the different circumstances of lower limit play, it's still the best book available for Stud HiLo and Omaha HiLo.