@article{ma2014intelligent,
  title={Intelligent tutoring systems and learning outcomes: a meta-analysis},
  author={Ma, Wenting and Adesope, Olusola O. and Nesbit, John C. and Liu, Qing},
  journal={Journal of Educational Psychology},
  volume={106},
  number={4},
  pages={901–-918},
  year={2014}
}