A very useful book, "Aftermath," by Joel Meyerowitz. It's a huge book (and I mean HUGE. It's almost as big as my torso). Contains a treasure trove of high quality pictures of Ground Zero and the debris. Also shows the huge struggle the rescue workers went through clearing it up. It's also useful for refuting the Judy Wood crowd (look through this book and then tell me the Towers' steel was "dustified"). Recommended if you don't already have it.