To clarify: "Perl One-Liners Explained" is self-published, and "Perl One-Liners" is based on it and published by No Starch Press. Not sure why that makes "matters worse"?
He also self-published "Awk One-Liners Explained" and "Sed One-Liners Explained" and has a "Bash One-Liners Explained" in the pipeline, see http://www.catonmat.net/books
He also self-published "Awk One-Liners Explained" and "Sed One-Liners Explained" and has a "Bash One-Liners Explained" in the pipeline, see http://www.catonmat.net/books