Retrieved 2017-11-29. ↑ "Twitter Blocks Pro-Ukrainian Political Account for Russian Users", Brian RiesMay, Mashable, 19 May 2014. ↑ "Twitter 'Blocks' Access to Russia's Most Infamous Hackers", Kevin Rothrock, Global Voices Online, 27 July 2014. ↑ "South Korea tries to block Twitter messages from North".