Cammack, Paul Anthony, author
Leicester University Press, 1997
Buku Teks
Pinkney, Robert, author
Open University Press, 1993
Buku Teks
Dixon, Chris J., author
Routledge, 2015
Buku Teks
Handelman, Howard, author
Pearson/Prentice Hall, 2006
Buku Teks
Third World Foundation for Social and Economics Studies, 1985
Buku Teks