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US2778952A
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Electronic impulse counting devices
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US2918123A
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Punched card machines
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GB757851A
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Improvements in and relating to the generation of electrical impulses corresponding to apertures in a punched card
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GB756116A
|
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Improvements in and relating to electronic impulse counting devices
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GB751923A
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Method and apparatus for automatically reading data representative markings applied to statistical record carriers
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GB752424A
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Improvements in or relating to punched card machines
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CA556455A
|
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Method for automatically reading markings applied to carriers
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CA561789A
|
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Generation of electrical impulses controlled by a perforated carrier
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