NCSC-TG-022: A Guide to Understanding Trusted Recovery in Trusted Systems, 30 December 1991. (Yellow Book)
You can download it from the following link: https://packetstormsecurity.com/files/download/14012/NCSC-TG-022.txt
Source: https://packetstormsecurity.com/files/14012/NCSC-TG-022.txt.html