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   Ejnar Hertzsprung
   Ejnar Hertzsprung (8 October 1873 – 21 October 1967) was a Danish chemist and astronomer. Hertzsprung was born in Copenhagen. In the period 1911–1913, together with Henry Norris Russell, he developed the Hertzsprung–Russell diagram. In 1913 he determined the distances to several Cepheid varia...
   Found op http://en.wikipedia.org/wiki/Ejnar_Hertzsprung
   
   

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