Bonea, Amelia, author
Oxford University Press, 2016
eBooks
Gunn, Geoffrey C.
Boulder Westview Press 1990,
Buku Teks
Stephens, Mitchell, author
Coloumbia University Press , 2014
Buku Teks
McNair, Brian, author
Routledge , 1996
Buku Teks
Kothari, Rajni, author
Little, Brown, 1970
Buku Teks