Festinger, Leon, 1919-1989
Social pressures in informal groups; a study of human factors in housing
Stanford University Press, 1950
 Buku Teks
Keesing, Roger M.
Kin groups and social structure
Holt, Rinehart and winston, 1975
 Buku Teks
Stangor, Charles
Social groups in action and interaction
Psychology Press, 2004
 Buku Teks
Focus groups in social research
by Michael Bloor ... [et al.]
Sage, 2002
 Buku Teks
Informal learning: the social evolution
American Society for Training and Development Research
American Society for Training & Development, 2013
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