Those look like M101-2s, but if they're postcard sized that can't be it, since real M101-2s are around 8"x10" and on thin stock. I don't think Steve D's suggestion of M101-3 works either, because although those were postcards issued by The Sporting News, there were only six of them, and they were color tinted rather than sepia. The Old Cardboard site shows the Marquard from that set, which is different from the Marquard in your picture:
http://www.oldcardboard.com/pc/pc757...?cardsetID=963
TCMA issued a set of postcard reprints of M101-2s in 1974, but those are black and white rather than sepia, and they have a big white rectangle in the corner with the year, in place of the brown rectangle with "Supplement to the Sporting News" in it, and a white strip added at the bottom with a typewritten line of stats.