Deaf people zone sign was used in Hamburg since the 1970s or the 80s?
https://www.google.com/maps/@53.5543957,10.0206724,3a,15.1y,4.44h,85.03t/data=!3m6!1e1!3m4!1sW4eFxM3g8hFEXny1lf-0iQ!2e0!7i13312!8i6656
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