Lüttinger, P., & Wolf, C. (2011). GESIS-Technical Reports. GESIS.
Lua i Stíl Chicago (17ú heag.)Lüttinger, Paul, agus Christof Wolf. GESIS-Technical Reports. Mannheim: GESIS, 2011.
Lua MLA (8ú heag.)Lüttinger, Paul, agus Christof Wolf. GESIS-Technical Reports. GESIS, 2011.
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