This is a fine example of a rare and hard to find Yankees single.
RARE Mark Koenig Single Signed Baseball 1927 NY Yankees JSA LOA
Calaméo - Fall21 Interactive Catalog
Uncle Mike's Musings: A Yankees Blog and More: February 2011
Mark Koenig Baseball Cards
Mark Koenig
Baseball Autographs- Sports Card and Sports Memorabilia Auctions
The Finest 1927 New York Yankees Team Signed Baseball on Earth., Lot #80011
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Mark Anthony Koenig (1904-1993) - Find a Grave Memorial
Mark Koenig Signed Autograph 1927 New York Yankees Bronx Bombers Murderer's Row