Article 88 CISG
(1) A party who is bound to preserve the goods in accordance with article 85 or 86 may sell them by any appropriate means if there has been an unreasonable delay by the other party in taking possession of the goods or in taking them back or in paying the price or the cost of preservation, provided that reasonable notice of the intention to sell has been given to the other party.
(2) If the goods are subject to rapid deterioration or their preservation would involve unreasonable expense, a party who is bound to preserve the goods in accordance with article 85 or 86 must take reasonable measures to sell them. To the extent possible he must give notice to the other party of his intention to sell.
(3) A party selling the goods has the right to retain out of the proceeds of sale an amount equal to the reasonable expenses of preserving the goods and of selling them. He must account to the other party for the balance.