A baseball cap Ernest Hemingway gave to his friend AE Hotchner is selling at RR Auction.
It's expected to make more than $9,000 on August 10.
Hotchner explains in a letter of provenance: "In 1955 I was on Ernest Hemingway's boat, the Pilar, with him, when a heavy squall erupted and blew my cap into the sea.
"Ernest handed me his cap, and said he had another in the hold, and this was the cap he gave me.
"I wore it every time I went out on the Pilar with him."
The two men met in 1948 and became close friends. They would travel around the world together in the intervening years, right until Hemingway's suicide in 1961.
Hotchner adapted a number of the Hemingway's works for stage and screen. He also wrote Papa Hemingway (1966), considered the definitive biography of the author.
A vast selection of autographs and letters from some of the 20th century's greatest writers is offered with a valuation of $10,000 and up.
It includes pieces from names as diverse as Joyce Carol Oates, Jean Paul Sartre and PG Wodehouse.
The collection consists of around 1,100 items and spans the years 1942 to 1987.
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