Are referendum results binding?

Constitution of the Republic of Latvia (last amended in 2005)

http://www.wipo.int/wipolex/en/text.jsp?file_id=190856

79. An amendment to the Constitution submitted for national referendum shall be deemed adopted if at least half of the electorate has voted in favour. A draft law, decision regarding membership of Latvia in the European Union or substantial changes in the terms regarding such membership submitted for national referendum shall be deemed adopted if the number of voters is at least half of the number of electors as participated in the previous Saeima election and if the majority has voted in favour of the draft law, membership of Latvia in the European Union or substantial changes in the terms regarding such membership.