Papers organized your books and book chapters just as it organized your articles. In fact, you can create books out of a collection of PDFs if you would like to, and use this feature as yet another way of organizing your files. We have created a video covering how you can create books, book chapters, and convert files to these formats in Papers. As with all our tutorials, you can view this content in a browser as well: http://www.youtube.com/watch?v=WOzbaVP6XaM