They reworked and honed older vaudeville routines into Who’s on First. So they wrote parts of it. Here’s a link that goes into it: abbottandcostellofanclub.com/whos-on-first/
abbottandcostellofanclub.com
Abbott and Costello's classic "Who's on First?" routine | Abbott & Costello Fan Club
Tracing the history of Abbott and Costello's classic "Who's On First?"
