Jones, Fred R. (Fred Rufus), 1893-, author
McGraw-Hill, 1963
Buku Teks
Mottram, Ralph Hale
Arrow Books, 1968
Buku Teks
Petherbridge, F.R., author
Cambridge University Press, 2013
Buku Teks
Cochrane, Willard W., author
University of Minnesota Press, 1964
Buku Teks
edited by Don F. Hadwiger and Ross B. Talbot
Academy of Political Science, 1982
Buku Teks