Wade, Terence
Cambridge University Press, 2009
Buku Teks
Crabb, George
Grosset & Dunlap, 1945
Buku Referensi
Nandy, Milon
Composite Study Aid Publications, 1993
Buku Referensi
Crabb, George
New York Grosset and Dunlap [t.th.]
Buku Teks
editor, Laurence Urdang
Macmillan Reference Books, 1995
Buku Referensi