Issues of sub-national referendums regulated at the national level

Azerbaijan

Answer

Devolution
Creation/merger/abolition of sub-national territories
Public policy issues

Source

Constitution of the Republic of Azerbaijan:

Article 134

Nakichevan republic has an independentstatus.

IV. Constitution of the AzerbaijanRepublic, laws of the Azerbaijan Republic, decrees of the President of theAzerbaijan Republic and decrees of Cabinet of Ministers of the AzerbaijanRepublic are obligatory on the territory of Nakhchyvan Autonomous Republic.

Constitution of the Republic of Azerbaijan
http://azerbaijan.az/portal/General/Constitution/doc/constitution_e.pdf