HULL, C. H. (1981). SPSS UPDATE 7-9. McGraw-Hill Book Company.
Lua i Stíl Chicago (17ú heag.)HULL, C. Hadlai. SPSS UPDATE 7-9. McGraw-Hill Book Company, 1981.
Lua MLA (8ú heag.)HULL, C. Hadlai. SPSS UPDATE 7-9. McGraw-Hill Book Company, 1981.
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