Hickler, Holly
Allyn and Bacon, Inc., 1980
Buku Teks
Sharples, Mike, 1952-
Ellis Horwood Limited, 1985
Buku Teks
Johnson, Falk S.
Houghton Mifflin, 1965
Buku Teks
Kirk-Greene, C. W. E.
Foulsham, 1992
Buku Teks
Bielby, Nicholas
Scholastic Publications, 1994
Buku Teks