Artikel Jurnal
Soetjiningsih
EGC, 1987
Buku Teks
Boyle, D.G.
Hutchinson University Library , 1971
Buku Teks
Austria : The Opec Fund For International Development, 2006,
Majalah, Jurnal, Buletin
Romeo, Luigi
Amsterdam John Benjamins 1979
Buku Referensi