Those sources are all over the map. <http://voiceofrussia.com/news/2014_03_29/Crimea-switches-to-Moscow-time-0223...> says that the main Simferopol clock changed at 22:00 March 29, and also that Crimea changed at 14:00 March 30. <http://voiceofrussia.com/news/2014_03_30/Crimea-Sevastopol-set-clocks-to-Mos...> says that the main clock in Sevastopol changed at 02:00 March 30, and that it also changed at 21:00 March 29. Although it's unlikely that all these reports are correct, it does seem that people changed their clocks pretty much at a random time. Since our entry is for Europe/Simferopol, I'm mildly inclined to go with the headlines on the first article and use the main Simferopol clock; this would have the advantage of leaving experimental tz database alone.