George Pattison 
Routledge Philosophy Guidebook to the Later Heidegger [PDF ebook] 

Martin Heidegger is one of the most controversial thinkers of the twentieth century. His writings are notoriously difficult: they both require and reward careful reading.The Later Heidegger introduces and accesses:* Heidegger’s life and the background to his later works* The ideas and texts of some of his influential later works, including The Question concerning Technology, The Origin of the Work of Art, and What is Called Thinking?* Heidegger’s continuing importance to philosophy and contemporary thought.