4[2]Graham S,Barker G P.The down side of help:An attributional-developmental analysis of helping behavior as a low-ability Cue[J].Journal of educational Psychology,1990,(82):7-14.
5[3]Nelson-Le Gall S.Help-seeking behavior in lemming[J].Gorrdon E.W.ed.Review of research in education,1985,(112):290-311.
