source: West Berlin had its own postal administration, separate from West Germany's, which issued its own postage stamps until 1990.
target: The post administration of West Berlin was separate from West Germany's. It issued its own  postage stamps until 1990.
references: The post administration of West Berlin was separate from West Germany's. It issued its own  postage stamps until 1990. West Berlin had a post office which gave stamps until 1990 and was different from West Germany's. West Berlin had its own post office system.  The system was separate from West Germany.  West Germany released its own postage stamps until 1990. West Berlin had its own postal administration and postage stamps until 1990.  It was separate from West Germany's. West Berlin had its own postal government. It issued stamps until 1990. West Berlin had a postal administration that was separate from West Germany's. West Berlin's created its own postage stamps until 1990. West Berlin had its own postal service until 1990. West Berlin had its own post offices. They were not part of West Germany's post office system. West Germany had its own postage stamps until 1990. West Berlin had its own postal administration which issued its own postage stamps until 1990.    This was separate from West Germany's postal system. West Berlin had its own postal administration, separate from West Germany's, which issued postage stamps until 1990.