Germany, regional Obligatory referendum [LOR] - Länderneugliederung

Art 29 GG

(3) The referendum shall be held in the Länder from whose territories or parts of territories a new Land or a Land with redefined boundaries is to be established (affected Länder). The question to be voted on is whether the affected Länder are to remain as they are or whether the new Land or the Land with redefined boundaries should be established. The proposal to establish a new Land or a Land with redefined boundaries shall take effect if the change is approved by a majority in the future territory of such Land and by a majority in the territories or parts of territories of an affected Land taken together whose affiliation with a Land is to be changed in the same way. The proposal shall not take effect if within the territory of any of the affected Länder a majority reject the change; [...]

(6) A majority in a referendum or in an advisory referendum shall consist of a majority of the votes cast, provided that it amounts to at least one quarter of those entitled to vote in Bundestag elections. (..)

Reference: Basic Law for the Federal Republic of Germany Published: 23.05.1949 Last amended 21. July 2010

New delimitation of the federal territory.

If in one referendum area the result is negative, then the merger of the states is rejected - besides in the area of the new to be created state a majority of 2/3rd of the votes approved the merger