Hartmut Ehrig Recent Trends in Data Type Specification, 9th Workshop on Specification of Abstract Data Types Joint with the 4th COMPASS Workshop, Caldes de Malavella, Spain, October 26-30, 1992, Selected Papers COMPASS/ADT Lecture Notes in Computer Science 785 Springer 1994 3-540-57867-6 db/conf/compass/compass92.html