SIMBAD references

The properties of variations of the recurrence time (cycle-length) T_C of outbursts in dwarf novae (DN) and their relation with the parameters of outbursts are reviewed. DN of the following types were considered: SU UMa, Z Cam, U Gem, intermediate polars. The method of O-C residuals revealed that generally the changes of T_C are prominent, but not chaotic and the O-C diagrams often display well defined trends. Variations of the mass and angular momentum transport through the disk are in accordance with the changes of T_C in DN with long orbital periods and long mean T_C, like CH UMa and DX And. Changes of the mass inflow rate from the donor can contribute in DN with short T_C, like SS Cyg or AH Her. The dramatic evolution of the DN outbursts in GK Per can be understood in the framework of the recovery of the system from the classical nova explosion in 1901.