Duchacek, Ivo D.
Holt, Rinehart and Winston, 1965
Buku Teks
Emerson, Rupert
Cambridge: Harvard University Press, 1960
Buku Teks
Banton Michael
Oxford University Press, 1957
Buku Teks
Cleary, Joe
Cambridge University Press, 2009
eBooks
Cleary, Joe
Cambridge University Press, 2009
eBooks