[심리학 신문_The Psychology Times=이가영 ]

[참고자료]

1. Verywellmind, (2021), URL: https://www.verywellmind.com/preoperational-stage-of-cognitive-development-2795461

2. Joan Littlefield, Cook Greg Cook, (2005), CHILD DEVELOPMENT 

3. 유튜브, (2020), 피아제 인지발달단계론, URL: https://www.youtube.com/watch?v=YcixgyNzsq4&t=260s