Article 5. The Government may, when deemed necessary for the purpose of investigation in regard to the specified contract, cause the competent authorities to put pertinent questions to, or collect reports from, the other party to the contract or his sub-contractor or any other persons who do business with the said other party in connection with the said contract (including sub-contractors'subcontractors and other psrsons similar thereto), or to visit all these persons'places of business, places of operation or any other places to inspect books documents and other things kept there, or to put questions to witnesses.