Comment on "AdS nonlinear instability: moving beyond spherical symmetry"   [Class. Quantum Grav. 33 23LT01 (2016)]
  We argue that if the degeneracy of the spectrum of linear perturbations of AdS is properly taken into account, there are globally regular, time-periodic, asymptotically AdS solutions (geons) bifurcating from each linear eigenfrequency of AdS. 
Andrzej Rostworowski
hep-th gr-qc