Gilbert, Judy B.
Clear speech: pronunciation and listening comprehension in North American English: teachers resource book
Cambridge University Press, 2005
 Buku Teks SO
Flesch, Rudolf
The Art of clear thinking
Harper & Row, 1951
 Buku Teks SO
Shidle, Norman G.
Clear writing for easy reading
McGraw-Hill, 1951
 Buku Teks SO
Clancy, Tom
Clear and Present Danger
An Imprint of HarperCollins Publishere, 1989
 Buku Teks SO
Henny Marlyna
Peranan program clear to 10 dalam mempertahankan kemapanan Shampoo Clear
Fakultas Ilmu Sosial dan Ilmu Politik Universitas Indonesia, 2004
 UI - Skripsi Membership