SIMBAD references

We performed a detailed analysis of extensive photometric observations of a sample of the most active dwarf novae, that is, SU UMa stars which are characterized by supercycle lengths shorter than 120 d. We found observational evidence that supercycle lengths for these objects have been constantly increasing over the past decades, which indicates that their mean mass-transfer rates have been decreasing during that time. This seems to be a common feature for this type of stars. We present numerical results in each case and estimate time-scales of future development of these systems. This study is important in the context of evolution of dwarf novae stars and perhaps other cataclysmic variables.