321924 Hessler, R. M. (1992). Social research methods. Saint Paul, MN : West Pub..
Lua i Stíl Chicago (17ú heag.)321924 Hessler, Richard M. Social Research Methods. Saint Paul, MN : West Pub., 1992.
Lua MLA (9ú heag.)321924 Hessler, Richard M. Social Research Methods. Saint Paul, MN : West Pub., 1992.
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