Gray, P. (2013). Free to learn: Why unleashing the instinct to play will make our children happier, more self-reliant, and better students for life. Basic Books.
Robinson, C. C., Mandleco, B., Olsen, S. F., & Hart, C. H. (1995). Parenting styles and dimensions questionnaire. In Handbook of parenting (Vol. 3). Lawrence Erlbaum Associates.