This guideline about learning and teaching approaches includes a section about the card technique.
TIPPELT, R. and AMORÓS, A. (2003): Innovative and participative learning-teaching approaches within a project based training framework. Beiträge aus der Praxis der beruflichen Bildung Nº3. Mannheim (Germany): Internationale Weiterbildung und Entwicklung GmbH (InWent). [Accessed: 16.05.2011]