Legal provisions for optional referendums at national level

Romania
CONSTITUTIONOF ROMANIA
(Adopted 1991; lastamended 2003)
http://www.cdep.ro/pls/dic/site.page?id=371
ChapterII: The President of Romania
Article90: Referendum
(1) The Presidentof Romania may, after consultation with Parliament, ask the people of Romaniato express, by referendum,their will on matters of national interest.
LAW ON ORGANIZATION AND CONDUCT OF THEREFERENDUM
(Adopted2000; last amended 2013)
http://www.roaep.ro/legislatie/articole-legislatie/579/
Section3: Referendum on Issues of National Interest
Article11
(1) Preşedintele Rom?niei, după consultarea Parlamentului, poate cerepoporului să ?şi exprime voinţa prin referendum cu privire la probleme de interes naţional.
(2) Problemele care se supun referendumului şi data desfăşurării acestuiase stabilesc de Preşedintele Rom?niei, prin decret.