Artikel Jurnal
Artikel Jurnal
edited by Goerge Thomas Kurian, Graham T.T. Molitor
Macmillan Library Reference USA, 1996
Buku Referensi
Scott, A. C. (Adolphe Clarence), 1909-1985, compiler
Caves Book, 1984
Buku Teks
Hildebrand, David K., 1940-, author
John Wiley & Sons, 1977
Buku Teks