Full case and question :

In August 2020, Bauer Company (place of business in Berlin, Germany) signed a contract to buy Christmas trees and costumes from Tippo Company (place of business in Hanoi, Vietnam). The contract is silent on the choice of applicable law. According to the contract, Tippo shall deliver 500 Christmas trees (at price of 100 US dollars per tree) and 1000 costumes (at price of 50 US dollars per costume) to Bauer at least two weeks before the Christmas Eve on 24 December 2020. Tippo then failed to deliver the goods at the agreed date. To meet the market demand which was increasing close to the Christmas holiday, Bauer had no other option but to make orders for Christmas trees and costumes from another supplier at prices of 150 and 75 US dollars per item respectively. The goods ordered from Tippo did not arrive until 26 December 2020. Bauer then refused to pay for the goods delivered, requested the cancellation of contract and compensation for late delivery from Tippo. Tippo Company filed a lawsuit to the People's Court of Hanoi and requested Bauer to pay for the goods. Questions: 1. Which law shall govern the contract? 2. Could Bauer refuse payment, avoid the contract and request the damages in this dispute