"Regular Expressions Cookbook" may not be what you want

I bought this book for reasons I cannot remember, and I can't see why I did this in the first place. The intro chapters are not very useful, they do not cover anything besides 'Perl-style regexes' (they do cover differences between different Perl-style RE implementations though).
I'll probably keep it as a reference, if I ever need an RE for an already solved problem and Google would fail me.