Napier, R. W. (1981). Groups: Theory and experience (2nd.ed.). Houghton Mifflin.
Lua i Stíl Chicago (17ú heag.)Napier, Rodney W. Groups: Theory and Experience. 2nd.ed. Boston: Houghton Mifflin, 1981.
Lua MLA (9ú heag.)Napier, Rodney W. Groups: Theory and Experience. 2nd.ed. Houghton Mifflin, 1981.
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