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http://db.e-voting.cc/
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http://www.vvk.ee/voting-methods-in-estonia/engindex/
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http://www.vvk.ee/public/dok/Internet_Voting_Report_20052011_Final.pdf
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5. Drechsler, W., Madise, Ü.: Electronic Voting in Estonia. In: Kersting, N., Baldersheim, H. (eds.) Electronic Voting and Democracy. A Comparative Analysis, pp. 97–108. Palgrave Macmillan, Basingstoke (2004)