Heidegger, Martin..
What is called thinking ? : a translation of "Was Heisst Denken ?" /
with an introduction by J.G. Gray 
. - New York ; Grand Rapids ; Philadelphia  : Perennial Library,  1968 
. - XVI, 252 p.  21 cm. 
<br/><label>  ISBN: </label>0-06-090528-X