Signing of Hans-Dietrich Genscher contract: The Two Plus Four Agreement (officially the Treaty on the Final Settlement with Respect to Germany): 1990 treaty
based on 

https://upload.wikimedia.org/wikipedia/commons/thumb/3/32/Zwei-Plus-Vier-Vertrag.pdf/page42-1243px-Zwei-Plus-Vier-Vertrag.pdf.jpg
Traité de Moscou