about good book for studying English

Hello everyone!
Already in the middle of May.

In the March, I just worried too much about time's flying, however I really want to finish this course as soon as possible. Becase of my sons. I really love this cousre and I feel I am blessed very much to have this great chance. I try to be a better teacher and give back what I've experienced here to everyone.

Anyhow my question is that, "Do you have any good books which you've studied related to English learning? Right now I'm reading newpapers. Recommend me any good books, please.