Books
The Legend of the Regulators
Hunter and His Amazing Remote Control
The Penguin Who Lost Her Cool
Don't Pop Your Cork on Mondays
My Mouth is a Volcano
Calm Down Strategies:
Belly Breathing
Count to 10, 20, 30, etc. - whatever it takes
Think positive thoughts
Exercise (take a walk, go for a run, ride your bike, etc.)
Talk to a friend or trusted adult