https://creativecommons.org/publicdomain/zero/1.0/https://www.rawpixel.com/image/13989884
A cow's udder with vaccinia pustules and human arms exhibiting both smallpox and cowpox pustules. Coloured engraving by J. Pass, 1811.
Original public domain image from Wellcome Collection
Public DomainFree CC0 image for Personal and Business use