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.