Hewlett-Packard HP 28 Calculator
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HP-28C/S
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Hewlett-Packard HP 28 Calculator
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HP-28C
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HP28S clear case | This is a very rare clear cased Hewlett P… | Flickr
HP-28S Advanced Scientific Calculator Reference Manual Hewlett-Packard | eBay
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Discovering Calculus With the Hp-28 and the Hp-48: 9780070591790: Smith, Robert T., Minton, Roland B.: Books - Amazon.com
