Mell, Donald C.
Gale Research Company, 1982
Buku Referensi
Dieterich, Thomas G.
Center for Applied Linguistics, 1979
Buku Teks
Moulton, William G.
Modern Language Association of America, 1966
Buku Teks
Grierson, Herbert John Clifford, Sir, 1866-1960
Chatto and Windus, 1950
Buku Teks
Corcoran, Neil
Longman, 1993
Buku Teks