The writing on the reverse side is tough to decipher, I enlisted the help of Twitter and here's what we came up with:
This sends you & yours our very happy wish for the New Year and always -
Affectionately yours - Susanah
To Flora Reynolds Xmas 1939
Tarkington's second wife was Susanah Keifer Robinson, according to Wikipedia.
"Flora" could be "Floss," a nickname for Florence.
Found in "Rumbin Galleries" by Booth Tarkington. Published by Literary Guild, 1937.
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