Art. 82 CISG
(1) The buyer loses the right to declare the contract avoided or to require the seller to deliver substitute goods if it is impossible for him to make restitution of the goods substantially in the condition in which he received them.
(2) The preceding paragraph does not apply:
The Secretariat Commentary on Art. 67 of the 1978 New York Draft, predecessor to Art. 82 CISG, gives insight into the drafters' unterstanding on the eve of the 1980 Vienna Diplomatic Conference.
Overview of case law on Art. 82 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.