Enkvist, Nils Erik
Mouton, 1973
Buku Teks SO
Langacker, Ronald W.
Harcourt, Brace & World, 1968
Buku Teks SO
Ledefoged, Peter
Univeersity of Chicago Press, 1971
Buku Teks
by Bernard Bloch, George L. Trager
Baltimore, 1942
Buku Referensi
Moulton, William G.
Modern Language Association of America, 1966
Buku Teks SO