I plan to read a book which about English grammar

Recently I wrote some papers. I found out I had two serious problems. One is I don't know enough English vocabulary, another is I have bad grammar, so I decided to read a grammar book that was I bought by my when I was a freshman.

I plan to read a book which is about english grammar

Recently I wrote some papers, I found I had two serious problems. One is that I don't have enough English vocabulary, another is that I have bad grammar. So I decided to read a grammar book that I was bought by my when I was a freshman.