\begin{table}%t3
\caption{\label{tab3}Spectroscopic temperatures.}
\small%\centering
\par
\begin{tabular}{lrcc}
 \hline
\hline\noalign{\smallskip}
Nebula &   $T_{\rm eff}$\tablefootmark{1} &    $T_{\rm eff}$\tablefootmark{2}&    $T_{\rm eff}$\tablefootmark{3} \\
\noalign{\smallskip}
\hline
NGC~2392  &  40~000    &       45~000   &      47~000 \\
NGC~3242  &  75~000    &       75~000    &     75~000 \\
IC~418   &   39~000   &        37~000   &      36~000 \\
NGC~6826  &  44~000   &        50~000   &            \\
NGC~1535  &           &                 &      70~000 \\
IC~2448    &          &                 &      65~000 \\
\hline
\end{tabular}
\tablefoot{\tablefoottext{1}{Pauldrach et~al. (\cite{pauldrach});}
\tablefoottext{2}{Kudritzki et~al. (\cite{kudritzki});}
\tablefoottext{3}{Mendez et~al. (\cite{mendez}).}} 
\end{table}