edited by Coleen K. Withgott, Austin G. Anderson
Merriam-Webster, 1981
Buku Referensi
USA : Macmillan, 1996,
Buku Referensi
prepared under the editorial supervision of In Plain English, Inc.
Macmillan, 1996
Buku Referensi
Ochs, Linnea Leedham, author
Prentice-Hall, 1987
Buku Referensi
Lippincott , 2004
Buku Teks