The APM Body of Knowledge 5th edition has been written by practising project managers for practising project managers. It is designed to support frontline practitioners, consultants, advisers, senior managers in project-driven organisations, trainers, students, researchers, authors, publishers, librarians, information specialists and knowledge managers. It is used by the APM as a foundation for its membership, professional development and knowledge services.You can have a taste of some of the underlying definitions on the main APM website (PDF here), but basically they are charging money for the main dish.
APM Publishing Bookshop
I personally think they should be propagating this quite freely, since their membership route is now linked to an examination of this knowledge. I suspect many training providers may amortize the cost of the publication into their fees!
(Disclosure: I work for an organisation providing APM-accredited training.)