The said book and the entries therein, made as provided by the preceding section, shall, at all reasonable times, be open to the inspection of the mayor and the head of the police department of the city in which the auctioneer conducts his business, the district attorney of any county in which said city is located or which is a part of such city, and any person who shall be duly authorized in writing for that purpose by any or either of them and who shall exhibit such written authorization to such auctioneer.