The best book on parenting that I have ever come across is Listen, by Patty Wiplfer and Tosha Schore. They demonstrate consistently that calm presence and limit setting, day in day out, provides children with the necessary experience of being regulated while in connection. This builds their capacity to eventually manage strong emotions and greatly increases resilience.
This brief video is on how to handle your child when s(he) has been aggressive to another child and is part of a series that you may wish to check out on Youtube. Also, the Hand in Hand Parenting website is absolutely loaded with practical supports for parents. Hand in Hand Parenting