The History of Ethno-National Referendums 1791-2011

That is the title of a useful article by Matt Qvortrup (or here, both possibly gated).  Here is one excerpt:

To be sure, the British were not adverse to using the referendum as a tactical means of international politics (for example, in the case of the referendum in Moldova in 1857 — where the referendum was a convenient excuse to curb the influence of the Russian Empire after the Crimean War).  Here at the request of the British, a poll was held to unify the two territories Moldavia and Walachia (previously an area that had been under Turkish Suzerainty, though often dominated by Russia) under the name Romania.  However, it should be noted that the referendum was anything but free and fair; “Intimidations and arrests were not infrequent” and up to “nine-tenth of the population were denied the right to vote,” and that the vote only was held after some “bizarres manoevres diplomatiques.”

Here is an older (free) historical book on the employment of plebiscites to determine sovereignty.  Here is the new, well-timed, and not free March 2014 book by Matt Qvortrupp, on same topic.  Qvortrup, by the way, helped design the referendum for South Sudan.