Whenever a referendum is demanded against any measure passed by the municipal governing body, or whenever an initiative petition demands an amendment to the municipal charter, the question shall be submitted to the registered voters of the municipality for their approval or rejection at a special election called by the municipal governing body for that purpose or at the next general election, general municipal election or biennial or special town meeting if the municipality is subject to the Oklahoma Town Meeting Act.
Okla. Stat. tit. 11, § 15-109