\begin{table}%t6
\caption{\label{comp_abn_21peg}Comparison of the derived abundances with previous determinations for 21~Peg.}
%\centerline
{
\begin{tabular}{l|cc|cc|cc|cc}
\hline
\hline
Ion &\multicolumn{2}{|c|}{R08}&\multicolumn{2}{c|}{S81}      &\multicolumn{2}{c|}{S934}     &\multicolumn{2}{c}{D00}       \\
    &$\log (N/N_{\rm tot})$ & $n$ &$\log (N/N_{\rm tot})$ & $n$ &$\log (N/N_{\rm tot})$ & $n$ &$\log (N/N_{\rm tot})$  \\
\hline
\ion{He}{i }  & ~~$-$1.11 $\pm$ 0.04 &  7 &                &   &                &   &  &  \\	   
\ion{C}{i}    & ~~$-$3.66 $\pm$ 0.14 &  9 & --3.88          & 2 &                &   &  &  \\	   
\ion{C}{ii}   & ~~$-$3.65 $\pm$ 0.05 &  4 &                &   &                &   &  &  \\	   
\ion{N}{i}    & ~~$-$3.95 $\pm$ 0.12 &  4 &                &   &                &   &  &  \\	   
\ion{N}{ii}   & ~~$-$3.90:	        &  1 &                &   &                &   &  &  \\	   
\ion{O}{i}    & ~~$-$3.28 $\pm$ 0.11 & 18 &                &   &                &   &  &  \\	   
\ion{Ne}{i}   & ~~$-$3.76 $\pm$ 0.05 &  7 &                &   &                &   & --3.60 $\pm$ 0.16 & 3 \\	   
              & ~~--3.89 (\nlte)    &  1 &                &   &                &   & --3.82 (\nlte) & 1 \\  
\ion{Na}{i}   & ~~$-$5.60:         &  1 &                &   &                &   &  &  \\	   
\ion{Mg}{i}   & ~~$-$4.42 $\pm$ 0.12 &  5 &                &   &                &   &  &  \\	   
\ion{Mg}{ii}  & ~~$-$4.56 $\pm$ 0.03 &  7 & --4.72 $\pm$ 0.13 & 7 & --4.34 $\pm$ 0.05 & 4 &  &  \\	   
\ion{Al}{i }  & ~~$-$5.89	         &  2 & --6.05          & 2 &                &   &  &  \\	   
\ion{Al}{ii}  & ~~$-$5.70 $\pm$ 0.10 &  4 &                &   & --5.84          & 1 &  &  \\	   
\ion{Al}{iii} & 		                 &	   &                &   & --5.89 $\pm$ 0.21 & 2 &  &  \\	   
\ion{Si}{i}   & ~~$-$4.95:         &  1 &                &   &                &   &  &  \\	   
\ion{Si}{ii}  & ~~$-$4.49 $\pm$ 0.13 & 22 & --4.85          & 2 & --4.63 $\pm$ 0.07 & 2 &  &  \\	   
\ion{Si}{iii} & ~~$-$4.26:         &  2 &                &   &                &   &  &  \\	   
\ion{P}{ii}   & ~~$-$6.37 $\pm$ 0.06 &  3 &                &   &                &   &  &  \\	   
\ion{S}{ii}   & ~~$-$4.86 $\pm$ 0.13 & 26 &                &   &                &   &  &  \\	   
\ion{Ca}{i}   & ~~$-$5.84 $\pm$ 0.11 &  3 & --5.76          & 1 &                &   &  &  \\	   
\ion{Ca}{ii}  & ~~$-$5.98 $\pm$ 0.08 &  5 & --6.24          & 1 &                &   &  &  \\	   
\ion{Sc}{ii}  & ~~$-$9.37 $\pm$ 0.10 &  7 & --9.47          & 3 &                &   &  &  \\	   
\ion{Ti}{ii}  & ~~$-$7.23 $\pm$ 0.09 & 59 & --7.15 $\pm$ 0.16 &26 &                &   &  &  \\	   
\ion{V}{ii}   & ~~$-$7.98 $\pm$ 0.06 &  9 & --7.78 $\pm$ 0.16 & 6 &                &   &  &  \\	   
\ion{Cr}{i}   & ~~$-$6.29 $\pm$ 0.09 &  5 &                &   &                &   &  &  \\	   
\ion{Cr}{ii}  & ~~$-$6.20 $\pm$ 0.10 & 68 & --6.39 $\pm$ 0.25 &17 & --6.30 $\pm$ 0.01 & 5 &  &  \\	   
\ion{Mn}{i}   & ~~$-$6.54 $\pm$ 0.21 &  5 & --6.08          & 2 &                &   &  &  \\	   
\ion{Mn}{ii}  & ~~$-$6.51 $\pm$ 0.17 & 19 &                &   & --6.39 $\pm$ 0.10 & 3 &  &  \\	   
\ion{Fe}{i}   & ~~$-$4.52 $\pm$ 0.13 &108 & --4.80 $\pm$ 0.21 &32 &                &   &  &  \\	   
\ion{Fe}{ii}  & ~~$-$4.50 $\pm$ 0.12 &406 & --4.79 $\pm$ 0.18 &23 & --4.59 $\pm$ 0.05 &10 &  &  \\	   
\ion{Fe}{iii} & ~~$-$4.60 $\pm$ 0.06 &  3 &                &   &                &   &  &  \\	   
\ion{Co}{ii}  & ~~$-$6.75 $\pm$ 0.18 &  3 &                &   & --6.01 $\pm$ 0.01 & 3 &  &  \\	   
\ion{Ni}{i}   & ~~$-$5.71 $\pm$ 0.05 & 10 &                &   &                &   &  &  \\	   
\ion{Ni}{ii}  & ~~$-$5.61 $\pm$ 0.09 & 23 & --6.13          & 5 & --5.70 $\pm$ 0.02 & 4 &  &  \\	   
\ion{Zn}{i}   & ~~$-$6.96:         &  1 &                &   & --7.29 $\pm$ 0.11 & 3 &  &  \\	   
\ion{Sr}{ii}  & ~~$-$9.10:         &  2 & --9.18          & 2 &                &   &  &  \\	   
\ion{Y}{ii}   & ~~$-$9.76 $\pm$ 0.15 &  4 & --9.27          & 1 &                &   &  &  \\	   
\ion{Zr}{ii}  & ~~$-$9.48 $\pm$ 0.28 &  4 & -9.09          & 1 &                &   &  &  \\	   
\ion{Ba}{ii}  & ~~$-$9.19 $\pm$ 0.06 &  3 &                &   &                &   &  &  \\	 
\ion{Nd}{iii} & ~$-$10.09 $\pm$ 0.07 &  3 &                &   &                &   &  &  \\	   
\hline						\end{tabular}}
\smallskip
\par
In Col.~2, the meaning of a colon is the same as in Table~\ref{abundance}.\\ 
R08: this work; S81: \citet{sadakane81}; S934: \citet{smith93,smith1993,smith1994}; D00: \citet{Dworetsky00}.
\end{table}