Wardman M, Chintakayala PK, de Jong G. Values of travel time in Europe: review and meta-analysis. Transp Res Part A Policy Pract. 2016 Dec;94:93-111. doi: 10.1016/j.tra.2016.08.019
Hooper SR, Roberts JE, Nelson LM, Zeisel S, Kasambira D. Preschool predictors of narrative writing skills in elementary school children. Sch Psychol Q. 2010 Mar;25(1):1-12.