"Hans Kollwitz (14 May 1892 – 22 September 1971) was a German epidemiologist, eldest son of artist Käthe Kollwitz. He obtained his degree in medicine and psychotherapy in 1928. He was also a World War I veteran, in which he voluntarily served, after joining from the German Youth Movement where he was a Wandervogel." - (en.wikipedia.org 13.05.2021)
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