The “fuzzy front end” of product development: an exploratory study of German and Japanese innovation projects Herstatt, Cornelius Verworn, Birgit Nagahira, Akio 2002 - TUHH Open Research - frei zugänglich
The innovation process: an introduction to process models Verworn, Birgit Herstatt, Cornelius 2002 - TUHH Open Research - frei zugänglich