Legal provisions for mandatory referendums at national level

Sri Lanka
Constitutionof the Democratic Socialist Republic of Sri Lanka
(Adoptedin 1978, last amended in 2001)
http://www.priu.gov.lk/Cons/1978Constitution/Chapter_12_Amd.html
http://www.priu.gov.lk/Cons/1978Constitution/Chapter_13_Amd.html
(Mandatory referendum)
CHAPTERXII , Approval of certain Bills at Referendum, Article 83.
Notwithstandinganything to the contrary in the pro?visions of Article 82—
(a)a Bill for the amendment or for the repeal and replacement of or which isinconsistent with any of the provisions of Articles 1, 2, 3, 6, 7, 8, 9, 10 and11, or of this Article, and
(b)a Bill for the amendment or for the repeal and replacement of or which isinconsistent with the provisions of paragraph (2) of Article 30 or of paragraph(2) of Article 62 which would extend the term of office of the President or theduration of Parliament, as the case may be, to over six years,
shallbecome law if the number of votes cast in favour thereof amounts to not lessthan two-thirds of the whole number of Members (including those not present),is approved by the People at a Referendum and a certificate is endorsed thereonby the President in accordance with Article 80.