1Homans, G.. C. , The Human Group. New York:Harcourt, 1950.
2Laumann, E. O., Prestige and Association in the Urban Community. Indianapolis: Bodds- Merrill, 1966.
3Lazarsfeld, P. F., & Robert, K. M., Friendship as Social Process: A Substantive and Methodological Analysis. In Kendall, P. L. (Eds.), The Varied Sociology of Paul F.Lazarsfeld. New York: Columbia University Press, 1954.
4Woodworth, R. S. , Dynamic Psychology. In Murchison C. (Eds.), Psychologies of 1925. Worcester,MA: Clark University Press, 1925.
