Gormally, John, author
Prentice-Hall, 2000
Buku Teks
Hirst, D.M., author
Macmillan, 1976
Buku Teks
Wright, D. Franklin, author
D.C. Health, 1990
Buku Teks
Bradley, Teresa, author
John Wiley & Sons, 2002
Buku Teks
Wright, D. Franklin, author
D.C. Heath, 1990
Buku Referensi