Park, Bryan
Buku Teks
Wade, Terence
New York : Oxford University Press, 2002
Buku Referensi
Cowie, A.P., author
Oxford University Press, 1993
Buku Referensi
Carnie, Andrew, author
Wiley-Blackwell, 2013
Buku Teks
Collier-MacMillan International, 1969
Buku Teks