http://www.gukjenews.com/news/articleView.html?idxno=619157
http://www.anewsa.com/detail.php?number=1108537&thread=09r02
http://www.joongdo.co.kr/jsp/article/article_view.jsp?pq=201612240243
http://www.newsedu.co.kr/news/articleView.html?idxno=43739
http://www.newsdream.net/sub_read.html?uid=18449