Ed. Code, § 2401

Upon proper evidence of the receipt by any school district of the school supplies and equipment, and upon approval by the county superintendent of schools for payment of the invoice therefor, he shall draw his requisition upon the county auditor against the proper funds of the district in favor of the school supply revolving fund for the cost of the supplies and equipment plus a charge, not to exceed 10 percent of the cost, to cover expenses of handling and possible losses. He shall thereupon draw his requisition upon the county auditor against the school supply revolving fund in favor of the vendor of the supplies and equipment in the amount of the approved invoice. The requisitions, when allowed and signed by the county auditor, constitute warrants on the county treasurer against the funds of the district and against the school supply revolving fund, respectively.