On ebay, as of this posting, is a letter from Ben and Bio to Zelda Fitzgerald. I assume that something was sent with the letter, possibly a copy of Bio’s book “The Boy of Bethlehem”?
ALS. 1pg. 5” x 6”. Christmas 1931. New York City. An autograph letter signed “Bio De Casseres Benjamin De Casseres” addressed to Zelda Fitzgerald: “Dear Zelda: Here’s the latest news about the Virgin Birth – Bio De Casseres Benjamin De Casseres Christmas, 1931 New York City”. It is penned in green ink and has some light toning that affects nothing. Letters to Zelda are scarce, and this was sent when she was first hospitalized.