For the purposes of enforcing this chapter, the director may investigate any and all transactions, between producers and handlers, between nonprofit cooperative associations and producers, among handlers, or between handlers and wholesale customers, among wholesale customers, between handlers and consumers, or between wholesale customers and consumers. For that purpose, the director shall have access to, and may enter at all reasonable hours, any place where market milk is being stored, bottled, or manufactured, where market milk or any market milk product is being bought, sold, or handled, or where the books, papers, records, or documents which relate to those transactions are kept. He may inspect and copy those books, papers, records, or documents in any place within the state.