Vensus A.George
The council for reserch in values and philosophy, 2001
Buku Teks
Azumah, John Alembillah
Oneworld , 2001
Buku Teks
Bednarek, Monika
Cambridge University Press, 2018
eBooks
Kinown, Washington : U.S. Information Agency
Majalah, Jurnal, Buletin
Higham, Nicholas J., 1961-
Routledge, 2006
Buku Teks