APA   Click to copy
Li, I., Dey, A. K., & Forlizzi, J. (2012). Using context to reveal factors that affect physical activity. ACM Transactions on Computer Human Interaction, 19(1), 1–21.

Chicago/Turabian   Click to copy
Li, Ian, Anind K. Dey, and Jodi Forlizzi. “Using Context to Reveal Factors That Affect Physical Activity.” ACM Transactions on Computer Human Interaction 19, no. 1 (March 2012): 1–21.

MLA   Click to copy
Li, Ian, et al. “Using Context to Reveal Factors That Affect Physical Activity.” ACM Transactions on Computer Human Interaction, vol. 19, no. 1, Mar. 2012, pp. 1–21.

@article{ian2012a,
  title = {Using context to reveal factors that affect physical activity},
  year = {2012},
  month = mar,
  issue = {1},
  journal = {ACM Transactions on Computer Human Interaction},
  pages = {1-21},
  volume = {19},
  author = {Li, Ian and Dey, Anind K. and Forlizzi, Jodi},
  month_numeric = {3}
}