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      Scientific American April 1939

      Problems

      Are Scientific American Readers Interested in Mathematical Problems? To Settle this Debated Question The Editors Offer These as a Test

      • By Leonard Kaplan on April 1, 1939

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      More in the April 1939 issue of Scientific American
      • 50 Years Ago, April 1939
      • Camera Angles Round Table, April 1939
      • Telescoptics, April 1939
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