in reply to Which non-Perl books made you a better (?:Perl )?Programmer?
The Elements of Style and the MLA Handbook -- because sometimes you need to plead your case to non-developers.
Strong ++ for Strunk and White. No matter what you're writing, it will make it better. Some of its concise, direct, no nonsense advice might even be applied to writing Perl and certainly to POD.
Original 1918 edition online here: Elements of Style.
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