Kunkel, Paul
New York Laurence King 1999,
Buku Referensi
Kunkel, Paul, author
Laurence King Publishing, 1999
Buku Referensi
Holdsworth, Brian, author
Butterworths, 1988
Buku Teks
Rockport Publisher, 1997
Buku Referensi
Peatman, John B.
McGraw-Hill, 1980
Buku Teks