\begin{table}%t1
\caption{Elemental abundances with respect to total hydrogen.}\label{abun}
%\centering
\par
\begin{tabular}{lc}
\hline
\hline
Element & Abundance \\
\hline
D$^{(1)}$  & 1.5($-$05) \\
O$^{(2)}$  & 3.2($-$04) \\
N$^{(3)}$  & 7.5($-$05) \\
    C$^{(4)}$  & 1.32($-$04) \\
S$^{(4)}$  & 1.86($-$05) \\
Si$^{(5)}$ & 2.9($-$05) \\
\hline
\noalign{\smallskip}
\multicolumn{2}{l}{1 Linsky et~al. (\cite{Linsky}).}\\
\multicolumn{2}{l}{2 Meyer et~al. (\cite{Mey98}).}\\
\multicolumn{2}{l}{3 Meyer et~al. (\cite{Mey97}).}\\
\multicolumn{2}{l}{4 Savage \& Sembach (\cite{Savag96}).}\\
\multicolumn{2}{l}{5 Black et~al. (\cite{Black78}).}
\end{tabular}
\end{table}