SIMBAD references

We present the results of a long-term variability survey of the old open cluster NGC 6791. The BVI observations, collected over a time span of 6 years, were analyzed using the ISIS image subtraction package. The main target of our observations were two cataclysmic variables, B7 and B8. We have identified possible cycle lengths of about 25 and 18 days for B7 and B8, respectively. We tentatively classify B7 as a VY Sculptoris type nova-like variable or a Z Camelopardalis type dwarf nova. B8 is most likely an SS Cygni type dwarf nova. We have also extracted the light curves of 42 other previously reported variable stars and discovered seven new ones. The new variables show long-period or nonperiodic variability. The long baseline of our observations has also allowed us to derive more precise periods for the variables, especially for the short-period eclipsing binaries.