Art. 97 CISG
(1) Declarations made under this Convention at the time of signature are subject to confirmation upon ratification, acceptance or approval.
(2) Declarations and confirmations of declarations are to be in writing and be formally notified to the depositary.
(3) A declaration takes effect simultaneously with the entry into force of this Convention in respect of the State concerned. However, a declaration of which the depositary receives formal notification after such entry into force takes effect on the first day of the month following the expiration of six months after the date of its receipt by the depositary. Reciprocal unilateral declarations under article 94 take effect on the first day of the month following the expiration of six months after the receipt of the latest declaration by the depositary.
(4) Any State which makes a declaration under this Convention may withdraw it at any time by a formal notification in writing addressed to the depositary. Such withdrawal is to take effect on the first day of the month following the expiration of six months after the date of the receipt of the notification by the depositary.
(5) A withdrawal of a declaration made under article 94 renders inoperative, as from the date on which the withdrawal takes effect, any reciprocal declaration made by another State under that article.
Overview of case law on Art. 97 CISG: UNCITRAL Digest
The UNCITRAL Digest on the CISG can be used as a starting point to discover the relevant case law on this article.