Kennedy, X.J.
Harper Collins, 1991
Buku Referensi
Chang, H.C.
Edinburgh University Press, 1973
Buku Teks SO
Wessels, Charlyn
Oxford University Press, 1991
Buku Teks SO
edited by Sylvan Barnet, Morton Berman, William Burto
Harper Collin College, 1992
Buku Teks
Artikel Jurnal