As defined by The Gale Encyclopedia of Psychology (2001), bullying is "An aggressive child who repeatedly victimizes a less powerful child with physical and/or emotional abuse." Also Harvard Children's Health (2006), define bullying as "Bullying is when one child keeps picking on, or acting roughly toward, another child who is smaller, weaker or defenseless. Bullying is not only physical fighting, but also can involve psychological, verbal or emotional abuse. Bullies try to control other children by picking on them or scaring them."

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