APA   Click to copy
Walker, E., Rummel, N., & Koedinger, K. R. (2009). Integrating Collaboration and Intelligent Tutoring Data in the Evaluation of a Reciprocal Peer Tutoring Environment. Research and Practice in Technology Enhanced Learning, 4(3), 221–251.

Chicago/Turabian   Click to copy
Walker, Erin, Nikol Rummel, and Kenneth R. Koedinger. “Integrating Collaboration and Intelligent Tutoring Data in the Evaluation of a Reciprocal Peer Tutoring Environment.” Research and Practice in Technology Enhanced Learning 4, no. 3 (December 10, 2009): 221–251.

MLA   Click to copy
Walker, Erin, et al. “Integrating Collaboration and Intelligent Tutoring Data in the Evaluation of a Reciprocal Peer Tutoring Environment.” Research and Practice in Technology Enhanced Learning, vol. 4, no. 3, Dec. 2009, pp. 221–51.

@article{erin2009a,
  title = {Integrating Collaboration and Intelligent Tutoring Data in the Evaluation of a Reciprocal Peer Tutoring Environment},
  year = {2009},
  month = dec,
  day = {10},
  issue = {3},
  journal = {Research and Practice in Technology Enhanced Learning},
  pages = {221-251},
  volume = {4},
  author = {Walker, Erin and Rummel, Nikol and Koedinger, Kenneth R.},
  month_numeric = {12}
}