Allan, Janice M., and Christopher Pittard. The Cambridge Companion to Sherlock Holmes. Cambridge UP, 2019.
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ISBN: 978-1107155855
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Critical essays on Sherlockian topics [WIP annotation]
https://openlibrary.org/books/OL28706259M/Cambridge_Companion_to_Sherlock_Holmes
https://search.worldcat.org/title/1048106014
❗Note: The hardback is very expensive, but the paperback is affordable, so I will prioritize those listings.
Cambridge website, Paperback listing