Wisconsin Statutes Police Regulations (Ch. 163 to 177) § 168.13. Required records

Every person receiving petroleum products in this state shall keep books and records of all petroleum products so received, together with bills of lading, waybills and other pertinent documents. Such books and records and other papers and documents shall, at all times during business hours of the day, be subject to inspection by the department and its inspectors, and are subject to inspection by the department of revenue in regard to the fee under s. 168.12(1). Such books, records and other papers and documents shall be preserved for not less than 4 years, unless the department, in writing, authorizes their destruction or disposal at an earlier date.