Art. 9. Non-Signatory Powers may adhere to the present Convention.
The Power which desires to adhere notifies its intention in writing to the Netherlands Government, forwarding to it the act of adhesion, which shall be deposited in the archives of the said Government.
That Government shall at once transmit to all the other Powers a duly certified copy of the notification as well as of the act of adhesion, stating the date on which it received the notification.