APA   Click to copy
Stadler, M., Niepel, C., & Greiff, S. (2016). Easily too difficult. Estimating item difficulty of microworlds. Computers in Human Behavior, 65, 100–106. https://doi.org/10.1016/j.chb.2016.08.025

Chicago/Turabian   Click to copy
Stadler, M., C. Niepel, and S. Greiff. “Easily Too Difficult. Estimating Item Difficulty of Microworlds.” Computers in Human Behavior 65 (2016): 100–106.

MLA   Click to copy
Stadler, M., et al. “Easily Too Difficult. Estimating Item Difficulty of Microworlds.” Computers in Human Behavior, vol. 65, 2016, pp. 100–06, doi:10.1016/j.chb.2016.08.025.

@article{stadler2016a,
  title = {Easily too difficult. Estimating item difficulty of microworlds},
  year = {2016},
  journal = {Computers in Human Behavior},
  pages = {100-106},
  volume = {65},
  doi = {10.1016/j.chb.2016.08.025},
  author = {Stadler, M. and Niepel, C. and Greiff, S.}
}