Flavell, Roger, author
Kyle Cathie, 1995
Buku Referensi
Merriam-Webster, 1989
Buku Referensi
Dando, Sylvia, author
McGraw-Hill Book, 1987
Buku Referensi
Hinkle, Deborah A.
MCGraw-Hill , 2002
Multimedia
Alderman, Eric, author
McGraw-Hill, 1988
Buku Teks