สืบค้น : การศึกษาในระบบ

https://th.wikipedia.org/wiki/%E0%B8%81%E0%B8%B2%E0%B8%A3%E0%B8%A8%E0%B8%B6%E0%B8%81%E0%B8%A9%E0%B8%B2%E0%B9%83%E0%B8%99%E0%B8%A3%E0%B8%B0%E0%B8%9A%E0%B8%9A
http://mediathailand.blogspot.com/2012/05/blog-post_3505.html
http://119.46.166.126/self_all/selfaccess7/m1/203/lesson1/education_1.php
https://panchalee.wordpress.com/2009/05/17/formal-education/