Legal provisions for optional referendums at national level

Libya
Constitution2011
https://www.constituteproject.org/constitution/Libya_2011.pdf
Article30
[…]
2.Choose a constitutive body for the formulation of a draft constitution calledthe
committeefor the elaboration of the constitution which shall present a draft constitutionto the Congress within a period not exceeding sixty days following its firstmeeting. The draft constitution shall be approved by the National GeneralCongress and be submitted to a yes-or-no referendum within thirty daysfollowing its adoption by Congress. If the Libyan people approve the constitutionby a two-thirds-majority of voters, the committee shall certify the text as theconstitution of the country and it shall be promulgated by Congress.