Re:Effort to Expose Russia’s ‘Troll Army’ Draws Vicious Reta...
by valcker on Tuesday May 31, 2016 @06:05AM
(#11805677)
Crimea was an "oblast" (or region) of Ukrainian SSR and the referendum was about re-establishing the Crimean Autonomous republic which was the case and was signed by Ukrainian SSR council: http://zakon1.rada.gov.ua/laws/show/712-12
During the separation of republics from USSR, Crimea stayed as a part of Ukraine (and voted for the independence of Ukraine, btw) which was a logical move in terms of infrastructure.
There were additional referendums, in 1992 and 1994, but they were asking questions with the reality of being part of Ukraine.