Fry, John, 1922-
MTP Press , 1978
Buku Teks
Hicks, Donald, author
Her Majesty's Stationary Office, 1976
Buku Teks
Collins, Charles, author
Oxford University Press, 1994
Buku Teks
Open University Press, 1998
Buku Teks
Syer, Jean C., author
Mosby , 2001
Buku Teks