1. Aber, J. L., Grannis, K. S., Owen, S., & Sawhill, I. V. (2013). Middle Childhood Success and Economic Mobility. The Social Genome Project. Brookings Institution EBooks. https://eric.ed.gov/?id=ED541844
2. Chall, J. S. (1995). Stages of Reading Development (2nd ed.). Wadsworth Pub Co.
3. Chall, J. S., & Jacobs, V. A. (2003). The Classic Study on Poor Children’s Fourth-Grade Slump. American Educator.
4. https://www.aft.org/periodical/american-educator/spring-2003/classic-study-poor-childrens-fourth-grade-slump
5. The Effects of Summer Vacation on Achievement Test Scores: A Narrative and Meta-Analytic Review