Benham, Frederic, author
Pitman Publishing Corporation, 1941
Buku Klasik
Benham, Frederic
New York, N.Y. Sir Issac Pitman 1941,
Buku Teks
Livesey, Frank
Longman , 1989
Buku Teks
Mitchell, Philip H., author
McGraw-Hill, 1956
Buku Teks
Ross, Alf, author
Longmans, Green , 1947
Buku Teks