\begin{table}%t1
\caption{\label{tab1}Elemental abundance of PNe with far-infrared data in addition to 
optical and UV data.}
\small%\centering
\par
\begin{tabular}{l c c c c c c c  c c c  }
 \hline
\hline\noalign{\smallskip}
PNe & He/H & C/H & N/H & O/H & Ne/H & S/H & Ar/H & $R$\tablefootmark{\natural} & Morph &  Ref.\\
& &$\times$10$^{-4}$&$\times$10$^{-4}$&$\times$10$^{-4}$&$\times$10$^{-4}$&$\times$10$^{-5}$&$\times$10$^{-6}$& (kpc) &   &\\
\hline
BD+30~3639 &         &  7.3  & 1.1  &  4.6  &  1.9  &  0.64 &  5.2    & 7.6  & R & a   \\      
Hb~5       &   0.123 &       & 4.5  &  4.5  &  2.2  &  0.70 &  5.5    & 6.0  & B & b   \\
He~2-111   &   0.185 &  1.1  & 3.0  &  2.7  &  1.6  &  1.5  &  5.5    & 6.2  & B & c   \\
Hu~1-2     &   0.127 &  1.6  & 1.9  &  1.6  &  0.49 &  0.42 &  1.1    & 7.9  & B & d   \\   
IC~418     &  $>$0.072 &  6.2& 0.95 &  3.5  &  0.88 &  0.44 &  1.8    & 8.8  & E & e   \\
IC~2165    &   0.104 &  4.8  & 0.73 &  2.5  &  0.57 &  0.45 &  1.2    & 9.8  & E & e, \tablefootmark{\ast} \\
IC~4191    &   0.123 &       & 1.49 &  7.7  &  4.7  &  1.6  &  4.45   & 7.0  & E & p   \\
M~1-42     &   0.161 & 10.5  & 7.5  &  8.3  &  4.4  &  2.8  &  8.6    & 3.0  & E & h   \\
Me~2-1     &   0.1   &  7.0  & 0.51 &  5.3  &  0.93 &  0.91 &  1.6    & 5.8  & R & r   \\
Mz~3       &  $>$0.080 & $<$16.  & 3.0  &  2.3  &  1.2  &  1.0  &  5.0 & 6.3 & B & q \\ 
NGC~40     &  $>$0.046 &  19 & 1.3  &  5.3  &  1.4  &  0.56 &  3.4    & 7.9  & E & f   \\
NGC~2022   &   0.106 &  3.66 & 0.99 &  4.74 &  1.34 &  0.63 &  2.7    & 9.4  & E & p   \\
NGC~2440   &   0.119 &  7.2  & 4.4  &  3.8  &  1.1  &  0.47 &  3.2    & 8.9  & B & g   \\
NGC~5315   &   0.124 &  4.4  & 4.6  &  5.2  &  1.6  &  1.2  &  4.6    & 6.3  & R & i   \\
NGC~5882   &   0.108 &  2.2  & 1.6  &  4.8  &  1.5  &  1.3  &  2.9    & 7.2  & E & e, $\ast$ \\
NGC~6153   &   0.140 &  6.8  & 4.8  &  8.3  &  3.1  &  1.9  &  8.5    & 6.9  & E & f   \\
NGC~6302   &   0.170 &  0.6  & 2.9  &  2.3  &  2.2  &  0.78 &  6.0    & 6.4  & B & j   \\
NGC~6445   &   0.151 &  7.4: & 2.4  &  7.4  &  2.0  &  0.79 &  3.8    & 5.8  & B & k   \\
NGC~6537   &   0.149 &  1.7  & 4.5  &  1.8  &  1.7  &  1.1  &  4.1    & 6.0  & B & c   \\
NGC~6543   &   0.118 &  2.5  & 2.3  &  5.5  &  1.9  &  1.3  &  4.2    & 8.1  & E & a   \\
NGC~6741   &   0.110 &  6.4  & 2.8  &  6.6  &  1.8  &  1.1  &  4.9    & 6.5  & E & l   \\
NGC~6818   &   0.099 &  5.4  & 1.26 &  4.8  &  1.27 &  0.94 &  2.7    & 6.6  & E & p   \\
NGC~6886   &   0.107 &  14.3 & 4.2  &  6.5  &  2.0  &  1.0  &  2.1    & 7.7  & E & o   \\
NGC~7027   &   0.106 &  5.2  & 1.5  &  4.1  &  1.0  &  0.94 &  2.3    & 7.4  & E & m   \\
NGC~7662   &   0.088 &  3.6  & 0.67 &  4.2  &  0.64 &  0.66 &  2.1    & 8.2  & E & l   \\
IC~2448    &   0.094 &  2.7  & 0.55 &  2.5  &  0.64 &  0.20 &  1.2    & 8.0  & E & s   \\
NGC~2392   &   0.080 &  3.3  & 1.85 &  2.9  &  0.85 &  0.50 &  2.2    & 8.4  & E & t   \\
NGC~6826   &   0.10  &  4.8  & 0.58 &  3.95 &  1.5  &  0.26 &  1.4    & 8.0  & E & u   \\
NGC~3242   &   0.092 &  1.95 & 1.35 &  3.8  &  0.90 &  0.28 &  1.7    & 8.1  & E & v   \\
NGC~6369   &   0.102 &   -   & 0.79 &  4.0  &  0.79 &  0.60 &  1.6    & 7.2  & R & v   \\
NGC~6210   &   0.092 &  1.2  & 0.70 &  4.9  &  1.2  &  0.74 &  2.3    & 7.0  & R & w   \\
NGC~2792   &   0.103 &  1.1  & 0.68 &  2.1  &  0.74 &  0.43 &  1.6    & 8.2  & E & x   \\
NGC~1535   &   0.085 &  1.6  & 0.21 &  2.6  &  0.53 &  0.13 &  1.1    & 9.9  & E & z   \\
\hline
\end{tabular}
\tablefoot{
\tablefoottext{\natural}{Galactocentric distance assuming the Sun is at 8~kpc from the center,
Morphology: R = round, E = elliptical, B = bipolar.}\\ 
\tablefoottext{\ast}{Higher resolution observations.}\\ 
\tablebib{a)~Bernard-Salas et~al. 2003, A\&A
406, 165; b)~Pottasch et~al. 2006; c)~Pottasch et~al. 2000, A\&A, 363,
767; d)~Pottasch et~al. 2003, A\&A, 401, 205; e)~Pottasch et~al. 2004,
A\&A, 423, 593; f)~Pottasch et~al. 2003, A\&A, 409, 599; g)
Bernard-Salas et~al. 2002, A\&A, 387, 301; h)~Pottasch et~al. 2007, A\&A, 471,
865; i)~Pottasch et~al. 2002, A\&A, 393, 285; j)~Pottasch et~al. 1999, A\&A, 347, 975; k)~van Hoof et~al. 2000, ApJ, 532, 384; l)
Pottasch et~al. 2001, A\&A, 380, 684; m)~Bernard-Salas et~al. 2001,
A\&A 367, 949; o)~Pottasch \& Surendiranath 2005, A\&A, 432, 139; p)
Pottasch et~al. 2005, 436, 965; q)~Pottasch \& Surendiranath 2005,
A\&A, 444, 861; r)~Surendiranath et~al. 2004, A\&A, 421, 1051; s)~Guiles, S.
et~al. 2007, ApJ, 660, 1282; t)~Pottasch et~al. 2008, A\&A, 481, 393;
u)~Surendiranath \& Pottasch 2008, A\&A, 483, 519; v)~Pottasch \& 
Bernard-Salas 2008, A\&A 490, 715; w)~Pottasch et~al. 2009, A\&A, 499, 249;
x)~Pottasch et~al. 2009, A\&A, 502, 189; z)~unpublished. } }
\end{table}