Flesch, Rudolf
Harper & Brothers, 1958
Buku Teks
(hapus1)
McGraw-Hill , 1990
Multimedia
Farbman, Evelyn, author
Houghton Miffiln, 1985
Buku Referensi
Radlauer, Ruth, author
Bowmar, 1971
Buku Teks
Perrin, Porter G., author
Scott, Foresman, 1950
Buku Teks