Here is a clip from an older post from 5 years ago...
that I wrote on May 31, 2006 post
It is basically from Tim Newcomb's article in issue #6 of OLD CARDBOARD.
It talks about both Gold Medal sets, the WS set of 12..... and the rarer group (like Klein, Averill, etc) as well
""To answer some of your questions (some info from the articles), the more commonly seen set of 12 Cardinals and Tigers World Series cards were issued as a promotion for Wheaties in 1934. The envelops have a return address for Gold Medal Foods, not Gold Medal Flour as they have been mistakenly called for years. 243,000 photos were mailed to 56,000 people between Oct. and Dec. 1934, fans received 1 card for each Wheaties box top. There is also an identical but far rarer group of cards (19 known so far) that match the Gold Medal Foods cards and these were thought to be have been offered to fans through radio broadcasts in Aug. 1933, and also the following summer. The Gold Medal Foods (Wheaties) cards are different from the R313 cards in that the name on front is more of a "Medium Pen" in size compared to the "Fine Pen" names of the National Chicle cards.""