Computer War / Code Duello Mass Market Paperback – January 1, 1973. Ace Double mass market paperback, 1973. "Code Duello| was first published in 1968, and is a novel in the author's "United Planets" series.

Computer War / Code Duello Mass Market Paperback – January 1, 1973. Ace Double mass market paperback, 1973. "Code Duello| was first published in 1968, and is a novel in the author's "United Planets" series.

Computer War / Code Duello Mass Market Paperback – January 1, 1973. Ace Double mass market paperback, 1973. "Code Duello| was first published in 1968, and is a novel in the author's "United Planets" series.