Closeup on ice hockey referee, location unknown, 13 March 2016. View public domain image source here https://www.rawpixel.com/image/6113906/photo-image-public-domain-people-iceFree Image from public domain licenseTurn coordinator clipart illustration vector. Free public domain CC0 image. https://www.rawpixel.com/image/10165858/vector-illustrations-public-domain-blackFree Vector from public domain licenseHockey player Silhouette illustration. Free public domain CC0 image. https://www.rawpixel.com/image/9778520/image-illustrations-public-domain-cleaningFree Image from public domain license