You can sign up for the GunSim Key Facts Mailing list. This means you get a short email with key facts about ballistics each week for a few weeks.
It adds up to a little mini-book on with a condensed overview of ballistics as applied to shooting.
Much easier than reading textbooks, just understaning you can put to use.
I don't give your email address to anyone else. Some free email addresses don't work with this.