Isn't there a way we can trace it,
Through the typeset or the paper?
Sorry. That went out with Sherlock Holmes.
'Name Of The Game'
Toobworld Central always (almost always) accepts references to fictional characters which have no qualifying attachments (like the name of their show, book, or movie source material) to mean that they actually do exist on Earth Prime-Time. And Sherlock Holmes, a resident in all three fictional universes, is no exception.
And just in case you didn't know, this is a reference to the classic version of Sherlock Holmes - the consulting detective from the Victorian era. And as portrayed by Jeremy Brett, not Peter Cushing, Douglas Wilmer, or Ronald Howard... as entertaining at their incarnations are.
Most definitely it couldn't be a reference to either of the two modern day incarnations as seen in 'Sherlock' and 'Elementary'. The latter is a CBS production set on an alternate Toobworld which never had a Sherlock Holmes (or an Ichabod Crane, for that matter) existing in their proper timeline. As for the former, Benedict Cumberbatch is playing the soul of the soul of the original 'Sherlock', now residing in Limbo.
At least that's the current theory for the TwD. It may yet change.....