Analysis of information sources in references of the Wikipedia article "Fandom" in English language version.
The earliest recorded examples of this fannish activity are from 1902...
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: CS1 maint: multiple names: authors list (link)Sherlockians called them parodies and pastiches (they still do), and the initial ones appeared within 10 years of the first Holmes 1887 novella, A Study in Scarlet.