NCSC-TG-015: A Guide to Understanding Trusted Facility Management, 18 October 1989 (Brown Book)
You can download it from the following link: https://packetstormsecurity.com/files/download/14005/NCSC-TG-015.txt
Source: https://packetstormsecurity.com/files/14005/NCSC-TG-015.txt.html