Mascull, Bill
HarperCollins Pub , 1996
Buku Teks
Pass, Chirtopher, author
Erlangga, 1997
Buku Referensi
Hauser, Rita E.
Oceana Publication , 1960
Buku Teks
Coultas, Barbara, author
Teach Yourself Books, 1990
Buku Teks
Price, Waterhouse
Price Waterhouse , 1984
Buku Teks