"Salinan arsip"(PDF). Diarsipkan dari versi asli(PDF) tanggal 2008-11-21. Diakses tanggal 2015-06-15.
psa.ac.uk
Bradley A. Thayer. Darwin and International Relations Theory: Improving Theoretical Assumptions of Political Behavior. 2010. Prepared for Presentation at the 60th Political Studies Association Annual Conference Edinburgh, Scotland. http://www.psa.ac.uk/journals/pdf/5/2010/1024_897.pdfDiarsipkan 2013-03-06 di UK Web Archive
Bradley A. Thayer. Darwin and International Relations Theory: Improving Theoretical Assumptions of Political Behavior. 2010. Prepared for Presentation at the 60th Political Studies Association Annual Conference Edinburgh, Scotland. http://www.psa.ac.uk/journals/pdf/5/2010/1024_897.pdfDiarsipkan 2013-03-06 di UK Web Archive