Keywords: Heinrich Rudolf Hertz.jpg Heinrich Rudolf Hertz Published in Lenard P 1930 Grosse Naturforscher T S Lehmanns Munich 1930 http //wellcomeimages org/indexplus/imageM0014750 html Photo first published 1894 at the latest Robert Krewaldt <gallery> File Heinrich Hertz jpg File Die Gartenlaube 1894 b 083 jpg</gallery> PD-old-70-1923 Cc-by-4 0 Heinrich Rudolf Hertz |