There are two broad kinds of style guide. There is the generic type, containing advice on such things as whether to use “different from” or “different than”. And there is the specific type, ie specific to a particular publication. For example, should “internet” be spelled with a lower case “i”, or as “Internet”?. The specific style guide will tell you.
You need both types, of course, but unfortunately it’s not quite as simple as your needing only two books or two documents.