Anger management

The past year I've noticed I've started having anger problems. It's not bad to where I hit or anything. It's just I get very irritated very easily and become easily angered by little things. I don't even understand why I get so angry. I was wondering if anyone knew any books that could help or anything really. I don't have the money to see someone or take a class for it so that's out of the question. I need help! Please and thank you!