@bookMeier_2015, place=Universität Paderborn, title=IT Project Portfolio Selection in the Presence of Project Interactions, author=Meier, Christian, year=2015 

@bookMutter_2015, place=Universität Paderborn, title=On the Activating Power of Gamification –  Empirical Evidence from an Online Community, author=Mutter, Tobias, year=2015 

@bookHerrmann_2014, place=Universität Paderborn, title=On Consumer Purchasing Behavior in Electronic Markets, author=Herrmann, Philipp, year=2014