\begin{table}%T1
  \caption{\label{tab:Period}The values for $\dot{P}/P$ of Cyg X-3, derived by fitting two different
models to the observations. A parabolic ephemeris assumes $\ddot{P} =
0$, whereas in the cubic ephemeris a second derivative of the period
unequal to zero is also taken
into account.}
 %\centerline
{
      \begin{tabular}{lcl}
    \hline
    \hline
    $\dot{P}/P$, fitted value                   & $\chi^2_{\rm red}$ & Reference                          \\
    \hspace{0.3cm}($10^{-6}$ yr$^{-1}$)         &                    &                                    \\
    \hline
    \multicolumn{3}{c}{Parabolic ephemeris}		                   	                                                       \\
    \hline
    $2.2 \pm 0.3^\dagger$  	& 1.41               & \citet[][]{vanderklis:1981}        \\
    $2.19 \pm 0.05^\dagger$	& 0.78               & \citet[][]{kitamoto:1987}          \\
    $1.6 \pm 0.1$	                        & 1.55               & \citet[][]{vanderklis:1989}        \\
    $1.2 \pm 0.4$	                        & 2.07               & \citet[][]{kitamoto:1995}          \\
    $1.05 \pm 0.04$	                        & 3.08               & \citet[][]{singh:2002}             \\
    \hline
    \multicolumn{3}{c}{Cubic ephemeris}			                   	                                                       \\
    \hline
    $4.0 \pm 0.6$$^\dagger$	& 1.36               & \citet[][]{vanderklis:1989}        \\
    $2.9 \pm 0.2$$^\dagger$	& 1.46               & \citet[][]{kitamoto:1995}          \\
    $1.4 \pm 0.3$$^\dagger$	& 2.96               & \citet[][]{singh:2002}             \\
    \hline
   \end{tabular}}
   \smallskip
$\dagger$ Value not quoted in the paper cited, but calculated by us from the published values of $P$ and $\dot{P}$.
 \end{table}