극이동이 이번생에 올지도 모르겠습니다

http://newscenter.berkeley.edu/2014/10/14/earths-magnetic-field-could-flip-within-a-human-lifetime/

http://blog.jinbo.net/chamcham/64

http://cafe.sayclub.com/cb_board.nwz?tbtype=&act=read&clubsrl=4389726&bsrl=10909&page=1&aseq=230537062