If you don't have one on your phone or tablet or computer you can use OFFLINE, get a paper one. They are very inexpensive and you can even find some at dollar stores. A little pocket one if you plan on doing any shorthand outside of your home.
This is helpful. Again, an offline one. You probably only need one and it doesn't have to be portable.
Either one of these might even have some grammar, etc., information in the front and or back of the book.
REFRESHER COURSE: There are several Grammar DUMMIES books you can find. If you think you need a refresher course or a new one, try the "Dummies" books. There's also a workbook that goes with it (at leas I think so). I was considering these, as I wouldn't mind a brush up of my own grammar. For me, these "DUMMIES" books makes learning more fun.