Ferguson, Elizabeth A., author
J.B. Lippincott, 1975
Buku Teks
Geeorge Allen , 1971
Buku Teks
Skidmore, Rex A. (Rex Austin), author
Prentice Hall International, 1991
Buku Teks
Ife, Jim, 1946-, author
Longman, 1997
Buku Teks
Skidmore, Rex A. (Rex Austin), author
Allyn and Bacon, 1995
Buku Teks