Abbott, Janet S.
Harcourt Brace Javanovich, 1987
Buku Teks
Buys, William E.
National Textbook Cmopany, 1994
Buku Referensi
Maley, Alan, 1937-, author
Cambrigde University Press, 1994
Buku Teks
Denita Biyanda Utami, author
Charite, 2016
UI - Makalah dan Kertas Kerja
Heinemann Educational Books, 1981
Buku Teks