Finding, John E.
Greenwood Press, 1997
Buku Teks
Wardiningsih Soerjohardjo, author
Serat Alam Media, 2017
Buku Teks
Jordan, R. R.
Collins ELT, 1980
Buku Teks
Brunn, Geoffrey
Oxford University Press, 1960
Buku Teks
Hearder, H.
Holt, Rinehart and Winston , 1966
Buku Teks