Each licensed supplier shall maintain his or her books and records in such manner as to enable the department to determine the gross sales of bingo supplies and equipment to licensed organizations. Invoices for the sale of bingo supplies and equipment shall include the name and license number of the organization to which the supplies were sold, the date and amount of the sale and an enumeration of the items sold. Each licensed supplier and formerly licensed supplier shall maintain his or her books and records for not less than 4 years and shall make them available at reasonable times for examination by the department or its authorized representatives.
Wis. Stat. § 563.26