https://wit.nts-corp.com/2013/10/16/280
https://www.wah.or.kr:444/Accessibility/define.asp
https://www.wah.or.kr:444/Participation/guide.asp
https://www.wah.or.kr:444/Participation/technique.asp
https://www.freeformatter.com/html-entities.html
https://opensource.org/licenses
https://en.wikipedia.org/wiki/Document_type_declaration