External links

• Birkhoff's biography − from National Academies Press
  National Academies Press
  National Academies Press was created by the United States National Academies, to publish the reports issued by the National Academy of Sciences, the National Academy of Engineering, the Institute of Medicine, and the National Research Council. It publishes nearly 200 books a year on a wide range...
  
  , by Oswald Veblen
  Oswald Veblen
  Oswald Veblen was an American mathematician, geometer and topologist, whose work found application in atomic physics and the theory of relativity. He proved the Jordan curve theorem in 1905.-Life:...
  
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