APA-čujuhus (7. p.)
Friedel, R. D. (2007). A culture of improvement: Technology and the Western millennium. MIT Press.
Chicago-čujuhus (17. p.)
Friedel, Robert D. A Culture of Improvement: Technology and the Western Millennium. Cambridge, MA: MIT Press, 2007.
MLA-čujuhus (9. p.)
Friedel, Robert D. A Culture of Improvement: Technology and the Western Millennium. MIT Press, 2007.
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