Burnell, Peter J.
Westview Press, 1986
Buku Teks
Norbu, Dawa
Routledge, 1995
Buku Teks
Worsley, Peter, author
Weidenfeld and Nicholson, 1978
Buku Teks
Kumari Jayawardena
Institue of social Studies, 1982
Buku Teks
Todaro, Michael P., author
Longman, 1992
Buku Teks