Principles of International Commercial Contracts, 1994 - UNIDROIT
Chapter 7 - Non-Performance
Section 4 - Damages
Article 7.4.6 - Proof of Harm by Current Price
(1) Where the aggrieved party has terminated the contract and has not made a replacement transaction but there is a current price for the performance contracted for, it may recover the difference between the contract price and the price current at the time the contract is terminated as well as damages for any further harm.
(2) Current price is the price generally charged for goods delivered or services rendered in comparable circumstances at the place where the contract should have been performed or, if the re is no current price at that place, the current price at such other place that appears reasonable to take as a reference.