In many countries, however, Parliament is the only authority able to call a referendum (Estonia, Finland, Latvia – on modifications of the terms of membership of the European Union –, Lithuania, Luxembourg, Malta, Sweden). In Belgium and Norway, where the constitution does not provide for referendums, Parliament has acted on the basis of a decision or specific acts of Parliament. In Austria, the National Council decides whether to hold a legislative or consultative referendum on issues of national importance; one-third of members of Parliament can submit a partial revision of the constitution to a popular vote. In Bulgaria, it is Parliament that decides, but the proposal to call a referendum may come not only from a quarter of members of Parliament but also the Council of Ministers or the President. In Hungary, Parliament decides following a proposal by the President, the Government, one-third of its members or 100,000 voters, while in “the former Yugoslav Republic of Macedonia” it decides in response to a proposal by the Government, a member of Parliament or 10,000 citizens. In Spain, a consultative referendum on an issue of particular importance is called by the King on the proposal of the Prime Minister following the authorisation of the Congress. In Greece¸ the President formally calls a referendum but the decision must be taken by a majority of members of Parliament on the proposal of the Government (on crucial national issues) or three-fifths of members of Parliament (on laws relating to important social issues).