author = { Mens, Tom AND Mens, Kim AND Steyaert, Patrick },

title = { Lecture Notes in Computer Science: OPUS: a formal approach to object-orientation },

publisher = {Springer Berlin Heidelberg},

isbn = {0302-9743},

isbn = {1611-3349},

year = {1994},

url = { http://slubdd.de/katalog?TN_libero_mab2 }