Kreveld, D. v. (1970). Structure and outcomes of study groups: A method of determining several properties of group structure and some relationships observed with group outcomes. Van Gorcum.
Lua i Stíl Chicago (17ú heag.)Kreveld, David van. Structure and Outcomes of Study Groups: A Method of Determining Several Properties of Group Structure and Some Relationships Observed with Group Outcomes. Assen: Van Gorcum, 1970.
Lua MLA (8ú heag.)Kreveld, David van. Structure and Outcomes of Study Groups: A Method of Determining Several Properties of Group Structure and Some Relationships Observed with Group Outcomes. Van Gorcum, 1970.
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