Smyth, Angela, author
Thorsons, 1994
Buku Referensi
Elliot, Rose, author
Chapmans Publisher Ltd., 1994
Buku Referensi
Friedrich W. Dittmar, author
Sterling Publishing Co.Inc, 1999
Buku Teks
Lu, Henry C., author
Black Dog & Leventhal Publishing, Inc, 1999
Buku Teks
Shackleton, Michael, author
John Harper Publishing, 2000
Buku Teks