↑ “Safeguard Data-Processing System”. The Bell System Technical Journal. 1975. Western Electric was the prime contractor for the Safeguard system and Bell Laboratories was responsible for the design
↑ Lester W. Grau; Jacob W. Kipp (1 tháng 7 năm 2002). “Maintaining Friendly Skies: Rediscovering Theater Aerospace Defense”. Aerospace Power. Although it was never fielded, it evolved into the Spartan missile.Quản lý CS1: nhiều tên: danh sách tác giả (liên kết)
↑ John W. Finney (25 tháng 11 năm 1975). “Safeguard ABM System to Shut Down”. New York Times. the utility of Safeguard to protect Minuteman will be essentially nullified in the future
