Hettne, Bjorn 1939-
Longman Scientific & Technical , 1995
Buku Teks
Schachter, Oscar, 1915-
Martinus Nijhoff , 1991
Buku Teks
Olson, William Clinton
Prentice Hall International, 1994
Buku Teks
Taba, Hilda
Harcourt Brece & World, 1962
Buku Teks
Midgley, James
Sage, 2014
Buku Teks