Thomas, David
Macmillan Education , 1990
Buku Teks
University of Tokyo Press, 1974
Buku Teks
Lubis, Mochtar, 1922-2004, author
Oxford University Press, 1989
Buku Teks
Kizaki, Satoko
Kodansho International , 1990
Buku Teks
Tonnies, Ferdinand
Routledge and Paul, 1955
Buku Teks