@Article {bfs.tapos98,
author = {E. Bertino and E. Ferrari and P. Samarati},
title = {Mandatory Security and Object-Oriented Systems: A Multilevel Entity Model and its Mapping onto a Single-Level Object Model},
journal = {TAPOS - Journal on Theory And Practice of Object Systems},
volume = {4},
number = {3},
pages = {183-204},
year = {1998}
}