Pitman, Randy, author
G.K. Hall & Co., 1992
Buku Teks
Loertscher, David V., author
Hi Willow Research & Publishing, 2009
Buku Referensi
Madeley, C.R.
World Health Organization, 1977
Buku Teks
Nisonger, Thomas E., author
Libraries Unlimited, 1992
Buku Referensi
Doll, Carol A., author
[American Library association, ], 2002
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