I know of no books that would help a child this age put another child’s aggression into proper perspective. The best solution is to arrange with the teacher to keep the two children separated. If that’s not possible, then the only solution might be to find another preschool program for your daughter. Or, if you can, keep her at home another year. I’d vote for the latter.
Family psychologist John Rosemond answers parents’ questions on his web site at www.rosemond.com.