The California attorney general's office said it has been asked by a group of libraries to investigate a decision by Kelley Blue Book Co. not to make the Kelley Blue Book New Car Price Manual available to libraries any more. The book, which lists prices that dealers pay manufacturers for automobiles, can tell consumers how much dealer profit is included in sticker prices. Duane Peterson, assistant to the attorney general, said it is possible that the decision could violate state antitrust or unfair business practice laws, depending on the reason. Mike Kelley of the Irvine-based publishing company declined to comment. Kelley also publishes a used-car Blue Book, which reportedly will remain available to libraries.