Fowler, W.S
Nelson, 1976
Buku Teks
Martin Montgomery ... [and others]
Routledge , 2007
Buku Teks
Taylor, Grant
Saxon Press, 1956
Buku Teks
Hewings, Martin, author
Cambridge University Press, 2006
Buku Teks
Ram Narain Lal Publisher, 1947
Buku Referensi