Yet by the time a 1991 European summit was held in the Dutch city of Maastricht, a plan for economic and monetary union (EMU) was written into a new EU treaty, to be ratified by member states later.

• 1991年欧洲峰会在荷兰的马斯特里赫特举行，同时实现经济和货币联盟的计划也被写入新的欧盟条约，但是稍后有待于成员国批准。