Ohta, Amy Snyder
Lawrence Erlbaum Associates Publ, 2001
Buku Teks
Kroll, B.
Cambridge University Press, 1990
Buku Teks
Cambridge University Press, 1990
Buku Teks
Harris, David P.
McGraw-Hill, 1969
Buku Teks
edited by Harold B. Allen
McGraw-Hill, 1965
Buku Teks