@inproceedings{SuiDietrichHeinrichetal.2019, author = {Li Sui and Jens Dietrich and Eva Heinrich and Manfred Meyer}, title = {A Web-Based Environment to Teach Introductory Programming based on a Bi-Directional Layered Notional Machine}, booktitle = {Konferenz: 21st Annual Conference on Innovation and Technology in Computer Science Education, 11.-13. Juli 2016 in Arequipa (Peru)}, year = {2019}, }