Puchta, Herbert
Cambridge University Press, 2014
Buku Teks SO
English Language Services; editor, Charles J. Hirsch, James A. Curtin
Collier/Macmillan, 1971
Buku Teks SO
Pack, Alice C.
Newbury House Pub., 1980
Buku Teks SO
Pincas, Anita
Macmillan, 1983
Buku Teks SO
Harrison, G.B.
Penguin Books , 1953
Buku Teks SO