Stability in $H^{1/2}$ of the sum of $K$ solitons for the Benjamin-Ono   equation
  This note proves the orbital stability in the energy space $H^{1/2}$ of the sum of widely-spaced 1-solitons for the Benjamin-Ono equation, with speeds arranged so as to avoid collisions. 
Stephen Gustafson, Hideo Takaoka, Tai-Peng Tsai