North-south differences of solar cycles
  A long-term variation is detected in the north-south differences of the solar activity, the phase difference of hemispheric cycles alternates by four Schwabe cycles. This variability is demonstrated by two different methods. It can be the related to the Gleissberg cycle. The variation of the sunspot group tilts is similar to the hemispheric phase lags on a shorter timescale. Some possible relations are mentioned. 
J. Murak\"ozy, A. Ludm\'any
astro-ph.SR