Cleary, Linda Miller
McGraw-Hill, 1993
Buku Teks
Lado, Robert
University of Michigan, 1957
Buku Teks
Miller, Charles D., author
Scott, Foresman and Co., 1978
Buku Teks
Farmer, R.D.T.
Blackwell Scientific Publ., 1977
Buku Teks
Hattersley, Michael E.
McGraw-Hill , 1997
Buku Teks