Flesch, Rudolf, author
Harper & Row, 1951
Buku Teks
Rainbolt, George, author
Wadsworth and Cengage Learning, 2012
Buku Teks
Shipps, Steve, author
Blackwell Publishing, 2008
Buku Teks
Dobelli, Rolf, author
Kepustakaan Populer Gramedia, 2019
Buku Teks
Dow, Gwyneth M.
Pergamon Press, 1971
Buku Teks