International Society for Educational Information, 1989
Buku Teks
Miller, Roger LeRoy, author
Pearson education, 2010
Buku Teks
Ebeinsten, William
Prentice-Hall, 1967
Buku Teks
Forbis, William H.
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Buku Teks
Corwin, Edward S., author
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Buku Teks