"A historical mystery needs to have just enough sense of an otherwhen to make it noticeably different from our own time." Generally, this is taken to be a modern work set at least 40 years in the past.
1.
Crime Thru Time
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Bibliography organized by author and by timeline, list of new releases, reviews, and message board. Affiliated with a discussion group.
2.
Beau Brummell Mystery Series
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Features an excerpt from one of the novels, information about the main character, the Regency era and the author.