APA   Click to copy
Greiff, S., Krkovic, K., & Nagy, G. (2014). The systematic variation of task characteristics facilitates the understanding of task difficulty. A cognitive diagnostic modeling approach to complex problem solving. Psychological Test and Assessment Modeling, 56, 83–103.

Chicago/Turabian   Click to copy
Greiff, S., K. Krkovic, and G. Nagy. “The Systematic Variation of Task Characteristics Facilitates the Understanding of Task Difficulty. A Cognitive Diagnostic Modeling Approach to Complex Problem Solving.” Psychological Test and Assessment Modeling 56 (2014): 83–103.

MLA   Click to copy
Greiff, S., et al. “The Systematic Variation of Task Characteristics Facilitates the Understanding of Task Difficulty. A Cognitive Diagnostic Modeling Approach to Complex Problem Solving.” Psychological Test and Assessment Modeling, vol. 56, 2014, pp. 83–103.

@article{greiff2014a,
  title = {The systematic variation of task characteristics facilitates the understanding of task difficulty. A cognitive diagnostic modeling approach to complex problem solving},
  year = {2014},
  journal = {Psychological Test and Assessment Modeling},
  pages = {83-103},
  volume = {56},
  author = {Greiff, S. and Krkovic, K. and Nagy, G.}
}