KET: http://www.cambridgeenglish.org/images/168163-cambridge-english-key-handbook-for-teachers.pdf
KET for schools:
http://www.cambridgeenglish.org/images/168174-cambridge-english-key-for-schools-handbook-for-teachers.pdf
PET: http://www.cambridgeenglish.org/images/168150-cambridge-english-preliminary-teachers-handbook.pdf