As near as I can tell, the Chicago Manual Of Style is the authority to which all publishers in the US and Canada appeal.
The soft cover version is reasonably priced, but I find using it difficult.
The online version—available for a yearly subscription fee—is much easier to use and includes regular emails of recent Q&A.
Strunk & White’s “The Elements of Style” is a handy distillation of the CMS, but it doesn’t seem to offer any advantage over the online version of the CMS. Granted, learning to locate something in the online CMS is a bit daunting at first, but it quickly gets easier as one “gets into” the pattern used. So, this little abbreviation isn’t as useful as it might have been before the CMS went online.
I’d appreciate your ideas or comments about the Chicago Manual of Style.

I love CMS and have used it since I was a lass, so it’s nice that you like it, too. Unfortunately, almost nothing you say here is correct.
First, CMS is only one of several important style guides (MLA, APA, AP, New York TImes, Bluebook, etc.) used by publishers. Second, there is no soft-cover edition of CMS. Third, the Q&A emails are free of charge and available to everyone, not just subscribers to the online edition. Finally, Strunk & White covers only a small percentage of the material found in CMS; there’s barely any relation.