00489cam a2200169 a 450000500170000000800410001702000150005803500150007305000190008810000150010724500490012226000370017130000110020844000490021965000250026865000260029320260818165838.0080808s1992    gw       r    000|0 eng d  a3540554939  a.b10462168 4aQA76.9 D3bL481 aLevene, M.14aThe nested universal relation database model  aBerlin :bSpringer-Verlag,c1992  a177 p. 0aLecture notes in computer science ;vno. 595 0aData base management 0aRelational data bases