SIMBAD references

We discuss the L-D correlation (possible dependence of radio luminosity on linear diameter) for supernova remnants (SNRs) in order to see whether the Σ-D relation actually exists and whether determination of SNR distances on the basis of the Σ-D relation is possible. We do not find any significant correlation, except for the M82 starburst galaxy for which a good Σ-D relation does exist. Finally, we suggest that a similar relation might exist for Galactic SNRs associated with large molecular clouds, indicating once again that the density of the SNR environment is probably the crucial parameter in SNR evolution.