Section 3. Every distributor, unclassified importer and unclassified exporter shall keep a complete and accurate record of all sales of fuel, including the name and address of the purchaser, the place and date of delivery, the gross receipts and number of gallons for each type of fuel sold, and a complete and accurate record of the number of gallons imported, produced, refined, manufactured, compounded or exported and the date of importation, production, refining, manufacturing, compounding or exporting. Every distributor, unclassified importer and unclassified exporter shall also deliver with every consignment of fuel to a purchaser within the commonwealth a written statement containing the date of purchase, the names of the purchaser and seller, the number of gallons delivered, and shall retain a duplicate of each statement. Said records and said written statements shall be in such form as the commissioner shall prescribe and shall be preserved by said distributors, said unclassified importers, said unclassified exporters and said purchasers respectively, for a period of three years and shall be offered for inspection at any time upon oral or written demand by the commissioner or his duly authorized agents.