Nyamsuren, Enkhbold, Han L.J. van der Maas, and Matthias Maurer. “Set-Theoretical and Combinatorial Instruments for Problem Space Analysis in Adaptive Serious Games”. International Journal of Serious Games 5, no. 1 (March 26, 2018). Accessed May 26, 2022. https://journal.seriousgamessociety.org/index.php/IJSG/article/view/219.