This is an authentic ticket stub from Steve Carlton's first career win in 1966 between the St. Louis Cardinals and the New York Mets. 

I've included for reference images of the 1966 schedule, a couple of grandstand tickets that proceed the game with scores on back along, a double header shortly after, and a psa graded person of the ticket to confirm that home game 57 corresponds to 8/5/1966.

He's signing at National, so great opportunity to sign and slab.