Worsley, Peter, author
Weidenfeld and Nicholson, 1978
Buku Teks
Pinkney, Robert, author
Open University Press, 1993
Buku Teks
Calvocoressi, Peter
Longman, 1991
Buku Teks
Barke, Michael, author
Longman Scientific & Technical, 1991
Buku Teks
Calvocoressi, Peter
Longman, 1992
Buku Teks