[1] SafeFrame (2017-06-15 15:33:23 +09:00) <https://www.iab.com/guidelines/safeframe/>
[2] (2017-01-25 12:04:23 +09:00) <http://www.iab.com/wp-content/uploads/2014/08/SafeFrames_v1.1_final.pdf>