صورة:Niels Bohr Albert Einstein by Ehrenfest.jpg

Niels Bohr and Albert Einstein.
The picture was taken at Ehrenfest's home in Leiden, the occasion was most likely the 50th anniversary of Hendrik Lorentz' doctorate (December 11, 1925).

http://www.dfi.dk/dfi/pressroom/kbhfortolkningen/

2006-05-23 (original upload date)

Paul Ehrenfest
Original uploader was Graf at de.wikipedia

PD-OLD.

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