NCSC-TG-029: Introduction to Certification and Accreditation Concepts, January 1994. (Blue Book)
You can download it from the following link: https://packetstormsecurity.com/files/download/14021/NCSC-TG-029.txt
Source: https://packetstormsecurity.com/files/14021/NCSC-TG-029.txt.html