Kramer, Mark (December 2011). "The Demise of the Soviet Bloc". The Journal of Modern History. 83 (4): 788–854. doi:10.1086/662547. S2CID144069540 – via The University of Chicago Press.
Anderson, Gary M. (1992-04-01). "Cannons, castles, and capitalism: The invention of gunpowder and the rise of the west". Defence Economics. 3 (2): 147–160. doi:10.1080/10430719208404723. ISSN1043-0717.
econlib.org
"Defense" by Benjamin Zycher in: The Concise Encyclopedia of Economics
Kramer, Mark (December 2011). "The Demise of the Soviet Bloc". The Journal of Modern History. 83 (4): 788–854. doi:10.1086/662547. S2CID144069540 – via The University of Chicago Press.
Anderson, Gary M. (1992-04-01). "Cannons, castles, and capitalism: The invention of gunpowder and the rise of the west". Defence Economics. 3 (2): 147–160. doi:10.1080/10430719208404723. ISSN1043-0717.
Sills, David L. (1972). International encyclopedia of the social sciences (Reprint ed.). New York: Macmillan Co. ISBN0-02-895710-5. OCLC3249566.
Keupp, Marcus Matthias (2020). The security of critical infrastructures risk, resilience and defense. Cham: Springer. ISBN978-3-030-41826-7. OCLC1153811682.