Oklahoma constitution
Article V: legislative power
Section 2

The first power reserved by the people is the initiative, and eight per centum of the legal voters shall have the right to propose any legislative measure, and fifteen per centum of the legal voters shall have the right to propose amendments to the Constitution by petition, and every such petition shall include the full text of the measure so proposed. The second power is the referendum, and it may be ordered (except as to laws necessary for the immediate preservation of the public peace, health, or safety), either by petition signed by five per centum of the legal voters or by the Legislature as other bills are enacted. The ratio and per centum of legal voters hereinbefore stated shall be based upon the total number votes cast at the last general election for the Office of Governor.