1. The law governing the contract under this Convention applies to the extent that it contains, in the law of contract, rules which raise presumptions of law or determine the burden of proof.

2. A contract or an act intended to have legal effect may be proved by any mode of proof recognized by the law of the forum or by any of the laws referred to in Article 9 under which that contract or act is formally valid, provided that such mode of proof can be administered by the forum.