Dine, Janet, author
Macmillan, 1991
Buku Teks
Oliver, M.C., author
Pitman, 1994
Buku Referensi
Bainbridge, Stephen M. , author
Foundation Press, 2002
Buku Teks
University of Iowa, 2018
Majalah, Jurnal, Buletin
general editor Michael Renshall
Butterworth, 1990
Buku Referensi