1

2

3

4
by Schawel, Christian, Billing, Fabian
Published 2011
Gabler

6
by Hartenstein, Martin, Billing, Fabian, Schawel, Christian, Grein, Michael
Published 2013
Springer Fachmedien Wiesbaden

7
by Schawel, Christian, Billing, Fabian
Published 2004
Gabler Verlag