1
Published 2011
OECD Publishing

2
Published 2003
OECD Publishing

3
Published 1999
Bundesministerium für Bildung und Forschung

4
Published 2006
OECD Publishing

5
Published 2008
W. Bertelsmann Verlag

6
Published 2002
W. Bertelsmann Verlag

7
Published 2006
European Union

8
Published 2002
OECD Publishing

9
Published 2011
OECD Publishing

10
Published 2007
Bundesministerium für Bildung und Forschung

11
Published 2011
OECD Publishing

12
Published 2001
OECD Publishing

13
Published 2004
OECD Publishing

14
OECD Publishing

15
Published 2010
OECD Publishing

16
Published 2004
Elsevier, Germany

18
Published 2006
OECD Publishing

19
Published 2004
OECD Publishing

20
by Keeley, Brian
Published 2008
OECD Publishing