No junk dealer or secondhand dealer shall purchase or otherwise receive in the course of his business any goods, articles, or things of value the ownership of which is in or which is claimed by any minor, or which may be in the possession of or under the control of a minor, unless the minor's parent or guardian shall state in writing that such transaction took place with such parent's or guardian's full knowledge and consent. It shall be the duty of such junk dealer or secondhand dealer to preserve and keep on file, and available for inspection, such written statements of consent.