Coulmas, Florian, author
Blackwell Publishers, 1998
Buku Teks
Andrew Spencer, Arnold M. Zwicky
Blacwell, 2001
Buku Teks
Tourist Division, Ministry of Transport, Government of India, 1956
Buku Teks
PBB. United Nations High Copmmissioner for Refugees
UNHCR, [date of publication not identified]
Buku Referensi
Cadle, Patrick, author
UNDP, 2008
Buku Teks