Boston, M. F., J. Hale, R. Kliegl, U. Patil, and S. Vasishth. “Parsing Costs As Predictors of Reading Difficulty: An Evaluation Using the Potsdam Sentence Corpus”. Journal of Eye Movement Research, vol. 2, no. 1, Sept. 2008, doi:10.16910/jemr.2.1.1.