NCSC-TG-028: Assessing Controlled Access Protection, 25 May 1992. (Violet Book)
You can download it from the following link: https://packetstormsecurity.com/files/download/14020/NCSC-TG-028.txt
Source: https://packetstormsecurity.com/files/14020/NCSC-TG-028.txt.html