Dickinson, Robert E.
Routledge & Kegan Paul Limited, 1951
Buku Teks
Meller, Helen, author
John Wiley & Sons, 2001
Buku Teks
Manchester University Press, 1999
Buku Teks
Dickinson, Robert E.
Routledge & Kegan Paul Ltd , 1956
Buku Teks
Dickinson, Robert E.
Kegan Paul, Trench, Trubner, 1947
Buku Teks