John Wolff's Web Museum - Slide Adding Machines

References Smithsonian Institution

Nice Vintage 1960's SWIFT HANDY CALCULATOR Desk Adding Machine

John Wolff's Web Museum - Monroe

Marchant silent speed model D calculator. one part has a date of

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John Wolff's Web Museum - Small Rotary Adding Machines

John Wolff's Web Museum - Small Rotary Adding Machines

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National Museum of American History

American Automatic Devices Co., est. 1915 - Made-in-Chicago Museum

Mystery Dating of the World-famous 'Millionaire' Calculating