The Symmetric Space and Homogeneous sine-Gordon Theories
  Two series of integrable theories are constructed which have soliton solutions and can be thought of as generalizations of the sine-Gordon theory. They exhibit internal symmetries and can be described as gauged WZW theories with a potential term. The spectrum of massive states is determined. 
C.R. Fernandez-Pousa, M.V. Gallas, T.J. Hollowood and J.L. Miramontes