1. INTRODUCTION
2. CV CATALOG, SYNOPTIC SURVEYS AND OBSERVATIONS
2.1. CV Catalog for Source Matching
2.2. Palomar Transient Factory
2.3. Catalina Real-Time Transient Survey
2.4. Lulin One-Meter Telescope
3. DATA ANALYSIS
3.1. Photometric Calibration
3.2. Timing Analysis
3.3. Lulin One-Meter Telescope Observations
4. POSSIBLE MECHANISMS OF LONG-TERM PERIODICITY
4.1. Precession of Accretion Disk
4.2. Hierarchical Triple Star
4.4. Other Possibilities
5. LONG-TERM MODULATION FOR THE INDIVIDUAL CVS
5.1. BK Lyncis (2MASS J09201119+3356423)
5.2. CT Boötes
5.3. LU Camelopardalis: 2MASS J05581789+6753459
5.4. QZ Serpentis: SDSS J155654.47+210719.0
5.5. V825 Herculis: 2MASS J17183699+4115511
5.6. V1007 Her: 1RXS J172405.7+411402
5.7. UMa 01: 2MASS J09193569+5028261
5.8. Her 12: SDSS J155037.27+405440.0
5.9. Coronae Borealis 06 & VW Coronae Borealis
5.10. Summary
6. CONCLUSION AND PROSPECT