The business entities which apply for exemption from business tax pursuant to Subparagraph 26 of Paragraph 1 of Article 8 of the Act shall present documents issued by the purchasing unit or the user unit of the Ministry of National Defense, stating the items, specifications, quantities, unit prices, total amount of the sale and the fact that such products conform to Subparagraph 26 of Paragraph 1 of Article 8 of the Act.