Oxford & IBH Pub, 1986"
Buku Teks
Reitsma, J.
Ruygrok, [date of publication not identified]
Buku Teks
Neushul, Michael
Hamilton, 1974
Buku Teks
Wilson, Carl L.
Holt, Rinehart and Winston, 1962
Buku Teks
Angladette, Andre
Paris Presses Universitaires de France 1959
Buku Teks