db/journals/jacm/SilberschatzK80.html Abraham Silberschatz Zvi M. Kedem Consistency in Hierarchical Database Systems. 72-80 1980 27 J. ACM 1 http://doi.acm.org/10.1145/322169.322176 db/journals/jacm/jacm27.html#SilberschatzK80 JACM/27/P0072.pdf