NCSC-TG-005: Trusted Network Interpretation of the TCSEC (TNI), 31 July 1987. (Red Book)
You can download it from the following link: https://packetstormsecurity.com/files/download/13996/NCSC-TG-005.txt
Source: https://packetstormsecurity.com/files/13996/NCSC-TG-005.txt.html