GUBA, E. G. (1981). Effective Evaluation. Jossey Bass Classic.
Lua i Stíl Chicago (17ú heag.)GUBA, Egon G. Effective Evaluation. Jossey Bass Classic, 1981.
Lua MLA (8ú heag.)GUBA, Egon G. Effective Evaluation. Jossey Bass Classic, 1981.
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