First response or Emergency first-aid?

Are there any good books out there for someone who's not a professional, who just wants to be prepared if a situation comes up. So I can know what to do before the ambulance arrives or if help is going to be awhile. I've looked at some wilderness first-aid books but they don't describe how to know the difference in sypmtoms if someone was having a heart attack or a cardiac arrest. Those are just examples. Thanks for any help.