Gilbert, Judy B.
Clear speech: pronunciation and listening comprehension in North American English: teachers resource book
Cambridge University Press, 2005
 Buku Teks
Shidle, Norman G.
Clear writing for easy reading
McGraw-Hill, 1951
 Buku Teks
Henny Marlyna
Peranan program clear to 10 dalam mempertahankan kemapanan Shampoo Clear
Fakultas Ilmu Sosial dan Ilmu Politik Universitas Indonesia, 2004
 UI - Skripsi Membership
Goldfard, Ronald L.
Clear understandings: a guide to legal writing
Random House, 1982
 Buku Teks
Evans, M. Stanton
Clear and present dangers a conservative view of america`s government
harcourt Brace Jovanovich,Inc., 1975
 Buku Teks