Danke für die Hilfe!
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\caption[Literaturübersicht]{Literaturübersicht}
\label{tab:Literaturübersicht}
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& & \multicolumn{3}{c}{Beispiel} & \multicolumn{3}{c}{Beispiel 2} \\
\multirow{-2}{*}{Studie}\tnote{a} & \multirow{-2}{*}{Studiendesign} & A & B & C & D & E & F \\
\midrule
Studie A & & & & & & & \\
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Studie Z & & & & & & & \\
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\begin{tablenotes}
\item [a] Test
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