I am trying to find out how to build a hidden door. It goes from the living room to the bedroom. I want it to have a bookshelf on both sides. The problem is that the wall is about 16 inches thick. So I need the hidden door also to be 16 inches thick. I cannot find a site that shows any plans for me to build my own hidden door. Are there any books that I can buy or a site that I can go to that will help me? I can use all the help that I can get. Thanks !!