(1) Each purchase order or contract issued or executed pursuant to this chapter shall be evidenced by a written order signed by the county purchasing agent, which shall give all significant details respecting such order or contract.
(2) A copy of such order shall be furnished the vendor, one (1) copy shall be furnished to the county accounting department, and at least two (2) copies shall be retained in the office of the county purchasing agent, one (1) of such copies to be filed in numerical order and the other alphabetically.