P. Pyla, J. Howarth, C. Catanzaro, and C. North. ACM-SE 44: Proceedings of the 44th annual Southeast regional conference, page 620--625. New York, NY, USA, ACM, (2006)
K. North, M. Franz, and G. Lembke. QUEM-Report ; H. 85 Arbeitsgemeinschaft Betriebliche Weiterbildungsforschung, Berlin, Ms.-Dr edition, (2004)Klaus North; Michael Franz; Gerald Lembke. Tab., graph. Darst 30
cm..