Headrick, D. R. (1981). The tools of empire: Technology and European imperialism in the nineteenth century. Oxford University Press.
Lua i Stíl Chicago (17ú heag.)Headrick, Daniel R. The Tools of Empire: Technology and European Imperialism in the Nineteenth Century. New York: Oxford University Press, 1981.
Lua MLA (9ú heag.)Headrick, Daniel R. The Tools of Empire: Technology and European Imperialism in the Nineteenth Century. Oxford University Press, 1981.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.