There's a very good chance that ALL of those layers contain asbestos. If it's all intact and solid, then layer over it and leave it alone. Just know that when you nail or screw through it. you'll probably break the 9x9s into pieces, and create the potential for airborne fibers. And that any work that pentrates the floor in the future will likely invade that broken material. Whatever you decide, please don't saw through any of this stuff.