Engelbert Westkämper Matthias Bengel Katja Fischer Basic Principles for Software Specification: Introduction to Subject Area Reference Case Study Production Automation. 9-22 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3147&spage=9 2004 conf/dfg/2004 SoftSpez Final Report db/conf/dfg/softspez2004.html#WestkamperBF04