Akcay, A., and N. Okur Akçay. “Comparison of Conceptual Knowledge Levels of Students Who Took and Did Not Take Preschool Education: Example of Earth, Sun, and Moon”. Southeast Asia Early Childhood Journal, vol. 9, no. 2, Sept. 2020, pp. 58-72, doi:10.37134/saecj.vol9.no2.4.2020.