Herbert Klaeren Elke Pulvermüller Awais Rashid Andreas Speck Aspect Composition Applying the Design by Contract Principle. 57-69 2000 conf/gcse/2000 GCSE http://link.springer.de/link/service/series/0558/bibs/2177/21770057.htm db/conf/gcse/gcse2000.html#KlaerenPRS00