Healey Joseph F. (2012). Statistics a tool for Social Research (9th.). Cengage Learning.
Lua i Stíl Chicago (17ú heag.)Healey Joseph F. Statistics a Tool for Social Research. 9th. UK: Cengage Learning, 2012.
Lua MLA (9ú heag.)Healey Joseph F. Statistics a Tool for Social Research. 9th. Cengage Learning, 2012.
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