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      Digital & 4-Year Archive

      Scientific American April 2001

      Hole in the Middle

      Not Too Big, Not Too Small, a New Class of Black Hole Emerges

      • By George Musser on April 1, 2001

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      More in the April 2001 issue of Scientific American
      • Erratum
      • Seeds of Concern
      • Whose Blood is it Anyway?
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