D. Bell, “Looking Back at the Bell-La Padula Model”,
Computer Security Applications Conference (ACSAC ’05), 
pp. 337-351, 2005.

The Bell-La Padula security model produced conceptual
tools for the analysis and design of secure computer systems.
Together with its sibling engineering initiatives, it
identified and elucidated security principles that endure today.
This paper reviews those security principles, first in
their own time, and then in the context of today’s computer
and network environment.