Benham, Frederic
New York, N.Y. Sir Issac Pitman 1941,
Buku Teks
Livesey, Frank
Longman, 1989
Buku Teks SO
Mitchell, Philip H.
McGraw-Hill, 1956
Buku Teks
Ross, Alf
Longmans, Green , 1947
Buku Teks SO
Reynolds, Lloyd G.
Richard D. Irwin, 1966
Buku Teks SO