Arthur Conan Doyle (2007). “The New Annotated Sherlock Holmes: The Complete Short Stories: The Return of Sherlock Holmes, His Last Bow and The Case-Book of Sherlock Holmes (Non-slipcased Edition) (Vol. 2) (The Annotated Books)”, p.1430, W. W. Norton & Company
Arthur Conan Doyle (2016). “Sherlock Holmes - The Novels: A Study in Scarlet, The Sign of the Four, The Hound of the Baskervilles, The Valley of Fear”, p.17, BoD - Books on Demand
Arthur Conan Doyle (2017). “The Complete Works of Arthur Conan Doyle (Illustrated): Complete Sherlock Holmes Books, The Professor Challenger Series, The Brigadier Gerard Stories… (Including Poetry, Plays, Historical Works, Spiritualist Writings & Personal Memoirs)”, p.6172, e-artnow