California Code, Government Code - GOV § 23374.13

The elections official of the principal county shall furnish to the officers of each precinct in the approved county the supplies and equipment as provided for in Sections 14105 and 14110 of the Elections Code. The elections official of each other affected county shall provide to the officers of each precinct the indexes of registration for the precincts of the approved county within their respective county. In addition, the elections official may, with the approval of the board of supervisors, furnish the original books of affidavits of registration or other material necessary to verify signatures.