1. Cristea et al. 2005. Cristea, P., Tuduce, R.: Automatic generation of exercises for self-testing in adaptive e-learning environments: Exercises on AC circuits, InternationalWorkshop on Authoring of Adaptive and Adaptable Educational Hypermedia (Part of WBE), WSEAS Publishing, S. 1126–1136, 2005
2. Higham 1998. Higham, N., J.: Handbook of Writing for the Mathematical Sciences, 2nd Edition, SIAM 1998
3. Hsiao et al. 2008. Hsiao, I., Brusilovsky, P., Sosnovsky, S.:Web-based parameterized questions for objectoriented programming,World Conference on E-Learning in Corporate, Government, Healthcare, and Higher Education, 2008
4. iHandySoft 2013. iHandySoft: QuickScan App, 2013 https://itunes.apple.com/de/app/quick-scan-strichcodescanner/id446067710?mt=8
5. Jäger 2016. Jäger, L.: QR-Codes in der Hochschullehre, Books On Demand 2016