Okla. Stat. tit. 11, § 11-15-109: Time for submission of measures to voters

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.