Brogan, D.W. (Denis William)
Harcourt, Brace & World, 1963
Buku Teks SO
Chilcote, Ronald H.
Routledge, 2000
eBooks
Curtis, Michael
Harper & Row, 1978
Buku Teks
Kesselman, Mark
Wadsworth and Cengage Learning, 2013
Buku Teks
Norton, Alan
Cheltenham Edward Elgar, 1997
Buku Teks