4Papalia, D. E., Olds, S.W. & Feldman, R.D. Human development (9th edition)[M]. New York: McGraw—Hiil, 2004.
5Hatzichristou, C. , Hopf, D. A multiperspective comparison of peer sociometric status groups in childhood and adolescence[J]. Child Development, 1996, 67 : 1085-1102.