Ball, Alan R., author
Macmillan, 1974
Buku Teks
Newton-Smith, W
Routledge & Kegan Paul, 1981
Buku Teks
Modelski, George
Free Press, 1972
Buku Teks
Magstadt, Thomas M., author
Wadsworth and Cengage Learning, 2013
Buku Teks
edited by Carolyn E. Carlson, Betty Blackwell
J.B. Lippincott , 1978
Buku Teks