Harry E. Winkler, correspondent for The Ring magazine from 1939 to 1953, collected thousands of boxing images from this Golden Age. Browse a gallery of portraits from the Harry E. Winkler ...

Ten years ago, German photographer Holger Keifel was looking through a few boxing books when he noticed that, in each photo, the boxer was in a similar position: hands up, tough face, ready to fight.

Claressa Shields (15-0, 3 KO) is back in the ring on Sunday facing Danielle Perkins in her hometown of Flint, Michigan.