UNHCR, 1997
Buku Teks
Keirstead, Burton Seely, author
Oxford University Press, 1956
Buku Teks
Webb, Leicester, author
F.W. Cheshire, 1954
Buku Teks
edited by Anna Rothe
H.W. Wilson, 1952
Buku Referensi
Iding Wangsa Widjaja, compiler
Inti Idayu Press, 1983
Buku Teks