What would be the good books for class 4 Flight Instructor Rating? to study or improve myself?
Thank you

"The Advanced Pilot's Flight Manual" is excellent, I wish someone introduced it to me during my commercial license.
"Air Command Weather Manual" is great for advancing your weather knowledge particularly in IFR flying.

there are a couple others, but I don't have them with me right now.....
Good Luck!

"Savvy Flight Instructor" is a great book on marketing as a flight instructor or flight school. The busy flight instructor is the one who knows how to market himself, not how well he knows flying.