1. OECD, “Early Childhood Education and Care Policy Review”, (2015), Information on: http://www.oecd.org/norway/Early-Childhood-Education-and-Care-Policy-Review.Norway.pdf
2. UN General Assembly, “Convention on the rights of the Child” Information on: http://www.refworld.org/docid/3ac6b38f9.html
3. M. F. Russo, Mathematics Teacher, 109, 351–354 (2016).
4. UNICEF, “Early Childhood Education for all” (2019), Information on: https://www.unicef.org/media/57986/file/Call-to-Action%20Statement-Early-Childhood-Educationfor-All.pdf
5. Kementerian Pendidikan Malaysia, “Pelan Pembangunan Pendidikan Malaysia 2013-2025” (KPM Kuala Lumpur, 2013).