1
by Berkun, Scott
Published 2009
O'Reilly Verlag

3
by Sammer, Petra, Heppel, Ulrike
Published 2015
Dpunkt.verlag

5
by Dräther, Rolf
Published 2014
O'Reilly Verlag

7
by Hoppe, Michael H.
Published 2018
Center for Creative Leadership