Oxford University Press, 1953
Buku Teks
Andrews, Jonathan; Briggs, Asa; Porter, Roy; Tucker, Penny; Waddington, Keir
Routledge, 1997
Buku Referensi
Rothstein, Andrew, author
Penguin Books , 1950
Buku Teks
Fry, Peter Somerset, author
Routledge , 2001
Buku Teks
Marwick, Arthur
London MacMillan 1992
Buku Teks