Christoper, author
Dinastindo, 1992
Buku Teks
Stephen Harris, Virginia Andrerson, Glen Banner, Valerie Bloch, Barbara Bouton, Forrest Haouletts, Anthony Keller, April D. Sessions, Dan L. Sessions, Rob Tidroew, editor
NRP, 1993
Buku Referensi
Acerson, Karen L., author
McGraw-Hill , 1988
Buku Teks
Rosenbaum, Daniel J., author
McGraw-Hill, 1988
Buku Teks
Young, Margaret Levine, author
IDG Books Wordwide, 1993
Buku Teks