Art. 137. Each national Bureau shall immediately forward information concerning protected persons by the most rapid means to the Powers in whose territory they resided, through the intermediary of the Protecting Powers and likewise through the Central Agency provided for in Article 140. The Bureaux shall also reply to all enquiries which may be received regarding protected persons. Information Bureaux shall transmit information concerning a protected person unless its transmission might be detrimental to the person concerned or to his or her relatives. Even in such a case, the information may not be withheld from the Central Agency which, upon being notified of the circumstances, will take the necessary precautions indicated in Article 140. All communications in writing made by any Bureau shall be authenticated by a signature or a seal.