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.
Phanikumar CV, Maitra B. Willingness-to-pay and preference heterogeneity for rural bus attributes. J Transp Eng A-Syst. 2007 Jan;133(1).