Legal provisions for mandatory referendums at national level

Constitution of the Independent State of Samoa 1960http://www.ilo.org/wcmsp5/groups/public/---ed_protect/---protrav/---ilo_aids/documents/legaldocument/wcms_126235.pdf

109. Amendment of Constitution(1) Any of the provisions of this Constitution may be amended or repealed by Act, and newprovisions may be inserted in this Constitution by Act, if a bill for any such purpose is supported atits third reading by the votes of not less than two-thirds of the total number of Members ofParliament (including vacancies) and if not fewer than 90 days elapse between the second and thirdreadings of that bill:Provided that no bill amending, repealing or adding to the provisions of Article 102 or the provisionsof this proviso shall be submitted to the Head of State for assent until it has been submitted to a pollof the electors on the rolls for the territorial constituencies established under the provisions of Article44 and unless it has been supported by two-thirds of the valid votes cast in such a poll. [?]