Article 16 1. This Convention shall be open for signature at the Headquarters of the United Nations from 30 August 1961 to 31 May 1962. 2. This Convention shall be open for signature on behalf of: (a) Any State Member of the United Nations; (b) Any other State invited to attend the United Nations Conference on the Elimination or Reduction of Future Statelessness; (c) Any State to which an invitation to sign or to accede may be addressed by the General Assembly of the United Nations. 3. This Convention shall be ratified and the instruments of ratification shall be deposited with the Secretary-General of the United Nations. 4. This Convention shall be open for accession by the States referred to in paragraph 2 of this article. Accession shall be effected by the deposit of an instrument of accession with the Secretary-General of the United Nations. Article 17 1. At the time of signature, ratification or accession any State may make a reservation in respect of articles 11, 14 or 15. 2. No other reservations to this Convention shall be admissible. Article 18 1. This Convention shall enter into force two years after the date of the deposit of the sixth instrument of ratification or accession. 2. For each State ratifying or acceding to this Convention after the deposit of the sixth instrument of ratification or accession, it shall enter into force on the ninetieth day after the deposit by such State of its instrument of ratification or accession or on the date on which this Convention enters into force in accordance with the provisions of paragraph I of this article, whichever is the later. 85