Elton, Geoffrey Rudolph, author
Sydney University Press, 1967
Buku Teks
Edited by Leon S. Sterling
Camberidge University Press , 1990
Buku Teks
Catt, Helena, author
Routledge , 1999
Buku Teks
edited by Kevin Taylor, Geoffrey Harding
Routledge, 2001
Buku Teks
Habermas, Jurgen, author
Heinemann, 1974
Buku Teks