Leach, James, author
Berghahn Books, 2004
Buku Teks
Artikel Jurnal
Woolford, Donald Mark, author
University of Queensland Press, 1976
Buku Teks
Robson, R.W., author
Pacific Publications PTY, 1954
Buku Teks
Wilson, Lindsay
McGraw-Hill , 1975
Buku Teks