\begin{table}%T2
      \caption{The classification of all 29 sources and spectral features found for each group.}
         \label{table 4}
$$
         \begin{array}{|c|c|c|}
            \hline\hline
            Classification &  Main\hspace{0.1cm}spectral\hspace{0.1cm}features &  {\it Sources} \\
                           &        Unit{:} ~\mu {\rm m}    &   (IRAS) \\
            \hline
A &  2.48, 2.58, 3.05, &  00172+4425, 01246-3248^*, 03374+6229, 05028+0106, \\
  & 5.20, 11.30, 13.70 &  12427+4542^\#, 12544+6615, 17419-1838^\#, 19017-0545^*, \\
  &                    &  21399+3516^* \\
\hline
B & 2.48, 2.58, 3.05,3.56, &  01080+5327, 02270-2619, 06226-0905, 12226+0102^*,\\
  & 3.90, 5.20, 11.30, 13.70 & 12447+0425^*, 15477+3943^*, 17556+5813^*, 20396+4757^*, \\
  &                    & 21358+7823, 21440+7324, 22036+3315^{*\#}  \\
\hline
C & 2.48, 2.58, 3.05,3.56,  &   03229+4721, 18398-0220, 19068+0544, 19248+0658^+ \\
  & 3.90, 5.20, 7.30, 11.30, 13.70  &  \\
\hline
D  &  11.30, 13.70 & 02293+5748^*, 21027+5309, 21489+5301^*, 23257+1038, \\
   &                   &  23320+4316^*  \\
\hline
         \end{array}
$$
%\begin{flushleft}
 Notes: a) "*'' means that the ISO SWS result is already published; b) "\#''
means that the objects do not show the 13.7~$\mu$m C$_2$H$_2$
feature; c)~"+''~means
 that the object does not show the 5.20~$\mu$m C$_3$ feature.
   \end{table}