Artikel Jurnal
Hanna, Michael S., 1939-, author
McGraw-Hill, 1991
Buku Teks
Critten, Peter, author
Churchill Livingstone, 1996
Buku Referensi
edited by Muriel Albers Bittel, Lester Robert Bittel and Jackson Eugene Ramsey
Grolier International, 1995
Buku Referensi
joseph, Cathy, author
A Roto Vision Book, 1999
Buku Referensi