Vouchers submitted for supplies furnished the state must set forth in itemized form the number or amount, and price of each article included in the account. Such vouchers must contain certificates signed by the head of the department or institution to the effect that the supplies were ordered by proper authority, that they were necessary in the public service, that the account is correct and just, and that the supplies charged for have actually been received in number and amount as charged.
Idaho Code § 67-2010