\begin{table}%t6
    %\centering
\par
       \caption{A comparison of
       differential rotation parameters $A$, $B$, and~$C$
       from Eq.~(15) for coronal bright points (Tables~\ref{table2}--\ref{table5}) with
       other results. R~-- remark.
\label{table6}
        }
        \begin{tabular}{llllllr}
        \noalign{\smallskip}
             \hline\hline
             \noalign{\smallskip}
Tracer/method       & Time       & $A \pm M_A$        & $-B \pm M_B$    & $-C \pm M_C$    & Source                          &  R \\
             \noalign{\smallskip}
             \hline
             \noalign{\smallskip}
Coronal bright points & 1967       & 14.65  $\pm$ 0.2   & &
& Dupree \& Henze (\cite{Dupree72})          &  1 \\ Coronal bright points &
1973       & 14.6   $\pm$ 0.3   & &                 & Golub et~al. (\cite{Golub74})             &  2 \\ Coronal bright points & 1998--1999 &
14.530 $\pm$ 0.032 & 2.68 $\pm$ 0.13 &                 & present
work, Table~\ref{table4}           &  3
\\ Coronal bright points & 1998--1999 & 14.677 $\pm$ 0.033 & 3.10
$\pm$ 0.14 &                 & present work, Table~\ref{table5}           & 4
\\
             \noalign{\smallskip}
             \hline
             \noalign{\smallskip}
Sunspots              & 1921--1982 & 14.522 $\pm$ 0.004 & 2.84 $\pm$ 0.04 &                 & Howard et~al. (\cite{Howard84})            &  5 \\
Sunspots              & 1921--1982 & 14.393 $\pm$ 0.010 & 2.95 $\pm$ 0.09 &                 & Howard et~al. (\cite{Howard84})            &  6 \\
Sunspots              & 1874--1976 & 14.551 $\pm$ 0.006 & 2.87 $\pm$ 0.06 &                 & Balthasar et~al. (\cite{Balthasar86})         &  7 \\
Sunspots              & 1853--1996 & 14.531 $\pm$ 0.003 & 2.75 $\pm$ 0.05 &                 & Pulkkinen \& Tuominen (\cite{Pulkkinen98})    &  8 \\
Sunspots              & 1880--1976 & 14.37  $\pm$ 0.01  & 2.59 $\pm$ 0.16 &                 & 
Braj\v sa et~al. (\cite{Brajvsa02}b)        &  9 \\
             \noalign{\smallskip}
             \hline
             \noalign{\smallskip}
H$\alpha$ filaments   & 1919--1929 & 14.48              & 2.16            &                 & d'Azambuja \& d'Azambuja (\cite{dAzambuja48}) & 10 \\
H$\alpha$ filaments   & 1972--1973 & 14.45              & 1.43            &                 & Adams \& Tang (\cite{Adams77})            & 11 \\
H$\alpha$ filaments   & 1972--1987 & 14.45  $\pm$ 0.15  & 0.11 $\pm$ 0.90 & 3.69 $\pm$ 0.90 & 
Braj\v sa et~al. (\cite{Brajvsa91})         & 12 \\
             \noalign{\smallskip}
             \hline
             \noalign{\smallskip}
Coronal bright points & 1998--1999 & 14.495 $\pm$ 0.026 & 1.89
$\pm$ 0.06 & 1.89 $\pm$ 0.06 & present work, Table~\ref{table2}           &
13 \\ Coronal bright points & 1998--1999 & 14.454 $\pm$ 0.027 &
2.22 $\pm$ 0.07 & 2.22 $\pm$ 0.07 & present work, Table~\ref{table3} & 14 \\
             \noalign{\smallskip}
             \hline
             \noalign{\smallskip}
LTRs                  & 1979--1991 & 14.25 $\pm$ 0.06   & 1.25 $\pm$ 0.19 & 1.25 $\pm$ 0.19 & 
Braj\v sa et~al. (\cite{Brajvsa00}a)        & 15 \\
LTRs                  & 1979--1991 & 14.16 $\pm$ 0.06   & 1.41 $\pm$ 0.19 & 1.41 $\pm$ 0.19 & 
Braj\v sa et~al. (\cite{Brajvsa00}a)        & 16 \\
             \noalign{\smallskip}
             \hline
             \noalign{\smallskip}
Magnetic              & 1967--1980 & 14.307 $\pm$ 0.005 & 1.98 $\pm$ 0.06 & 2.15 $\pm$ 0.11 & Snodgrass (\cite{Snodgrass83})                & 17 \\
Magnetic              & 1975--1991 & 14.42  $\pm$ 0.02  & 2.00 $\pm$ 0.13 & 2.09 $\pm$ 0.15 & Komm et~al. (\cite{Komm93})              & 18 \\
Magnetic              & 1997       & 14.00  $\pm$ 0.54  & 2.24 $\pm$ 1.22 & 1.78 $\pm$ 0.79 & Deng et~al. (1999)              & 19 \\
             \noalign{\smallskip}
             \hline
             \noalign{\smallskip}
Doppler               & 1966--1968 & 13.76              & 1.74            & 2.19            & Howard \& Harvey (\cite{Howard70})         & 20 \\
Doppler               & 1967--1984 & 14.05              & 1.49            & 2.61            & Snodgrass (\cite{Snodgrass84})                & 21 \\
Doppler               & 1981--1982 & 13.99  $\pm$ 0.06  &                 &                 & K\"uveler \& W\"ohl (\cite{Kuveler83})      & 22 \\
Doppler               & 1983--1986 & 13.92  $\pm$ 0.12  &                 &                 & Lustig \& W\"ohl (\cite{Lustig89})         & 23 \\
             \hline
            \end{tabular}
            \begin{flushleft}
1. OSO-4, Mg X spectroheliograms; \quad 2. Skylab, soft
X-rays; \quad 3. SOHO-EIT, automatic method, no height
correction; \\ 4. SOHO-EIT, automatic method, with height
correction; \quad 5. Mt. Wilson, sunspots; \quad 6.
Mt. Wilson, sunspot groups; \\ 7. Greenwich, sunspot groups;
\quad 8. Extended Greenwich, sunspots and sunspot groups; \\
9. Greenwich, only stable recurrent sunspot groups; \quad
10. Meudon; \quad 11. Big Bear, with height correction; \\
12. Big Bear and Kanzelh\"ohe, with height correction; \quad
13. SOHO-EIT, interactive method, no height correction; \\ 14.
SOHO-EIT, interactive method, with height correction; \\ 15.
Mets\"ahovi, microwave low brightness temperature regions, no
height correction; \\ 16. Mets\"ahovi, microwave low brightness
temperature regions, with height correction; \\ 17. Mt. Wilson,
photospheric magnetic fields; \quad 18. Kitt Peak,
photospheric magnetic fields; \\ 19. Huairou/Beijing, photospheric
high-latitude magnetic fields; \quad 20. Mt. Wilson,
photosphere, spectroscopic;\\ 21. Mt. Wilson, photosphere,
spectroscopic; \quad 22. Locarno, photosphere,
spectroscopic; \\ 23. Capri, photosphere, spectroscopic.  
        \end{flushleft}
     \end{table}