Wittgenstein, Ludwig 1889-1951.
On Certainty /
Ludwig Wittgenstein ; edited by G.E.M. Anscombe and G.H. von Wright ; translated by Denis Paul and G.E.M. Anscombe 
. - New York : Harper & Row, publishers,  1972 
. - vii, 90 p.  21 cm. 
 - (Harper torchbooks  ; TB 1686 )
<br/><label>  ISBN: </label>0-06-131686-5