archive.org/web/20161024103943/http://www.panoramio.com/user/969909?with_photo_id=86341012 operator: Panoramio described at URL: https://web.archive...
mouth) at Zeche Nachtigall, Dünkelberg quarry in Witten (Germany) German Eingang des Nachtigallstollens im Steinbruch Dünkelberg (Muttental), Witten object...
English operator: Panoramio described at URL: https://web.archive.org/web/20161012095934/http://www.panoramio.com/photo/4085580...
archive.org/web/20161024113020/http://www.panoramio.com/user/4347014?with_photo_id=77863782 operator: Panoramio described at URL: https://web.archive...
archive.org/web/20161022131831/http://www.panoramio.com/user/4662566?with_photo_id=50483988 operator: Panoramio described at URL: https://web.archive...
archive.org/web/20161103001302/http://www.panoramio.com/user/8900648?with_photo_id=124914496 operator: Panoramio described at URL: https://web.archive...
archive.org/web/20161017125846/http://www.panoramio.com/user/1406749?with_photo_id=42624230 operator: Panoramio described at URL: https://web.archive...
archive.org/web/20161012114737/http://www.panoramio.com/user/2742393?with_photo_id=18751464 operator: Panoramio described at URL: https://web.archive...
archive.org/web/20161017173758/http://www.panoramio.com/user/1406749?with_photo_id=48369116 operator: Panoramio described at URL: https://web.archive...
archive.org/web/20161024173505/http://www.panoramio.com/user/6046115?with_photo_id=84968386 operator: Panoramio described at URL: https://web.archive...