Artikel Jurnal
edited by Pamela S. Cenzer; Cynthia I. Gozzi
The Hawork Press , 1991
Buku Teks
edited Clare Jenkis; Mary Morley
Gower, 1991
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Eppen, Gary D., author
Prentice Hall International, 1988
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Markless, Sharon, author
Facet Publishing, 2006
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