Just adding to the info..
There are fakes out there of the Ted Williams "no #9", image will be slightly cropped and of lower quality (rescreened) and the back I believe is a gray color, not the offwhite/cream of the originals. Ive seen some cropped so much that the "Made in USA" line is no longer there.
ignore the 1939-46 and the 1947-66 set info if your actually interested in the age of the cards, many years in late 1940-1950s are a mixture of both styles. You can tell the approximate year by the size of the "MADE IN USA", or when they changed it to "Made in USA", "PRINTED IN USA", and "Printed in USA", and also sometimes by the color of the print (ie B&W).
Ted Williams (#9) showing is from 1939-41
Ted Williams (no #9) with a "MADE IN USA" is from 1946-1950
Ted Williams (no #9) with a "Printed in USA" is from 1957-1961
Joe DiMaggio (sepia) is from 1942-1946
Joe DiMaggio (B&W) is from 1952
Jackie Robinson is from 1948
basic info to help date these Exhibits is here (based on a story in the SCD back in the early 1990s)
http://centuryoldcards.com/1930/1939-66ExhibitInfo.html
1952 Exhibits Joe DiMaggio