Your first edition book Whither Mankind by Beard, 1928, published by Longmans, Green and Co has a value of $8 to $10
on its own. The card on the inside is not the signature of artist Samuel Cahan (1886-1974) as this signature is
not a match for his. He always signed his name in all capital letters. He grew up poor in Russia and never learned how to write in cursive.
This card would be that of another Samual Cahan, but not a famous one, so sorry.
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