If you can find a copy in a used bookstore or on eBay I'd recommend picking up Corporate Shadowguide. While it's 20 years out-of-date and takes a broader view, a more thorough exploration of how SR corporations work, including the legal insanity of extraterritoriality, you will never find.
Thanks for the suggestion,
Corporate Guide just showed up today. And would that be
Corporate Shadowfiles? Any help I can get with the corps would be good as modern economics/corporate stuuf is one of my weak points.