World's Series © 1934 Rock-ola.
Released in May 1934.
Design Patent DE90,927 applied for August-5-1933, issued October-24-1933.
Ball Shooter Patent Number 1,842,863.
Mechanical Patent No. 1,975,374 filed April-14-1934, granted October-2-1934.
Machine's picture.
Collector's Guide to Vintage Coin Machines - Richard M. Bueschel - Page 96
The Coin Machine Journal - January 1940 issue