Book Essentials, 1991
Buku Referensi
David B. Guralnik, editor in chief
William Collins Publishers, 1976
Buku Referensi
USA : Macmillan, 1996,
Buku Referensi
prepared under the editorial supervision of In Plain English, Inc.
Macmillan, 1996
Buku Referensi
Ochs, Linnea Leedham
Prentice-Hall, 1987
Buku Referensi