Sir Arthur Conan Doyle's comment about The Valley of Fear
From The Arthur Conan Doyle Encyclopedia
This ad published in The Sun (Baltimore) on 23 september 1914, the day after the first episode of The Valley of Fear in the same newspaper, included a handwritten quote from Arthur Conan Doyle mentioning the story was the last case of the detective.
« I fancy the "Valley of Fear" is the swan-song of Sherlock Holmes. Arthur Conan Doyle. »